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4 Attachment(s)
Sturdy and Fast all Steel CNC , my first build
Hi there,
I am on the way of my 1rst real build. The idea is to be fast and sturdy. I am building it for a friend by order. Its a smaller variant of a sturdy machine i designed not long ago for my self which i would build after that build, which will serve also to figure some points of the process.
I have a lot of questions and will appreciate any help with this one, as i would like to make it really right.
From my part, once finished, i will provide the Sketchup plans for free here, so anybody can use them if wished so.
Some of the design points:
1. All steel soldered construction. Overbuild for stiffness, avoiding weak elements in the design.
2. Money is not an issue for the frame or the length of the supported rails, so i am not going to go cheap to save 10cm of rail or steel profile.
3.This machine is for continuous 3d jobs routing plastic or composite epoxy based materials so a desired stable routing speed of 300ipm is the goal
4. Usual job size would be 800x400x160, hence that commands the gantry clearance and z design
5. 3d continuous very detailed jobs, > 24h sometimes, made me choose a low power spindle like the 0.8kw water cooled one. Electricity cost is an issue here
So i am at the point of finishing the design, still waiting for some details on the profiles. Already started purchasing the components. I hope in 3 months it should be making dust:afro:
Here are some pictures of the design, still not finished:
Attachment 9726Attachment 9727Attachment 9728Attachment 9729
Profiles used 180x80x4mm
gecko 540
Nema 23 low inductance motors , CNC routerparts Pro Rack and pinion drives 1:3, mod 1 rails, Hiwin HG 20 rails with long wide bearing blocks on all axis,
All plates are 10mm thick mild steel,
The doubts:
1. Now before i finish the design and order the profiles and plates , i wonder about the gantry weight. My design is 1000mm 180x80x4 profile with soldered over it at all sides 10mm steel plates. Basically the profile weight will be around 15kg ,reinforcing it will be another 50 kg+ the side plates another 10 + 2 motors and drives + Z another 12-15kg=more or less 100 kg. I am waiting for an advice from CNC routerparts about the gantry weight. If it heavy i can hollow some holes in the reinforcing plates to bring it to the desired weight , however i would like to reinforce it more than leave bare profile.
2.Another point here is that i am not sure if i can bolt to 4mm profile directly threading it or should be 10mm plates below RP rails, Hiwin rails, as i designed it
Notes:
- the table would sit on 2 more rails same of similar size soldered. This should raise it for the cable guides and stiffen it, to avoid twisting . I am contemplating making a case there and all electronics mounted inside the base of the machine
What do you think about the design?
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Re: Sturdy and Fast all Steel CNC , my first build
Hi,
Well the design looks strong but you have some quite major conflicts going on here.?
First the weight of the gantry really means your on the very edge of needing Servo's not steppers.!
Next because your using R&P then efficiency is very low so larger Nema34 motors will usually be needed to deal with this and the weight of the gantry.
The G540 is limited to 3.5A and 50V which isn't nearly enough for Nema 34 motors which you'll need at least 75Vdc or higher and more amps.
Nema 23 motors (even low inductance) just will just not be able to handle the Inertia this gantry's weight will put on them. Plus combined with R&P they will also struggle to give fast acceleration with that heavy gantry which you'll need for 3D work.
Even with larger Drives and higher 70Vdc voltage nema23 motors won't work with this weight gantry and high speed requirements.
Really I wouldn't recommend R&P for a machine this size and with your requirements for accuracy and 3D work, Ball-screws are the only way to go.!!. . . .You'll seriously regret using R&P.
Regards Steppers or servo's then I'd say lighten the gantry 20-30Kg and use Nema 23 motors running on 80Vdc drives with 70Vdc power supply and connected to 10mm pitch ballscrews.
If you don't lighten gantry then I'd say choose Servos has they will handle the inertia and speed much better.
Larger Nema 34 motors will handle the inertia at slower speeds but not do so well with the combination of speed and inertia has because they spin considerably slower than Nema23 motors they will struggle with reaching higher speeds anyway and the torque will be low at high speeds so with heavy gantry will struggle to handle inertia when changing direction.
So Above 80KG gantry at speed will need servos.
With Electrics in base of machine then I wouldn't recommend it has vibrations tend to loosen wires and don't mix well with sensitive electronics.!!
The 4mm steel will be fine for threads with rails.!
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Re: Sturdy and Fast all Steel CNC , my first build
Thanks. I am starting to realize this.
Let me explain something.
This build is a rip-off of my design for my next build which is meant to ride on 34 name Rack and Pinion.
I spend quite some time asking people around when i designed it, so it seems the overall opinion was that a 150kg gantry is quite well driven by 34 nema rack and pinion, i mean the acceleration and deceleration. There were even people on CNCzone that insisted that the gantry behaves well if is loaded more than 130kg so they made it heavy on purpose.
So everything started as i would like to test the RP on a real build, The nema 34 would raise the price, so i went for Nema 23 and started slowly underrating my original idea.
Now Just received an answer from CNCrouterparts and Ahron tells me what i suspected , that the g540 is not up to the task and i should couple their low inductance motors with better drivers, due to possible g540 overheating during long runs.
So it seems i am insisting on the RP drives:hysterical: . I like to test them and could not help . I am at the point of ordering the RP drives , racks and the low inductance Nema 23 . That means i must lower the gantry weight.
Ok, gantry weight.
Lets see. I can go back to 50 kg, complete gantry with Z, still keeping some reinforcement. Only eventual twisting should be considered, z is 300mm wide so no worry there in the other directions. Another point is that normally the jobs will be done with rough cuts by 1/4 router bits and fine passes 1/8 router bits, with passes equal to the width, routing wood as i said and that easy going special cast materials which route like MDB , so this is not a factor that would play in the final design.
Jazzcnc, i highly value your opinion. Why you believe the Chinese ball screws 2010 for example could give me better finish than the RP drives? All seem to be happy running RP drives, did i miss something? I know the table is not so big to really need RP.
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Re: Sturdy and Fast all Steel CNC , my first build
Quote:
Originally Posted by
silyavski
Jazzcnc, i highly value your opinion. Why you believe the Chinese ball screws 2010 for example could give me better finish than the RP drives? All seem to be happy running RP drives, did i miss something? I know the table is not so big to really need RP.
Those people on the Zone are probably only using R&P because.!
A: They are large long machines so ball-screws are harder to use.
B: They can't afford Us made Ball-screws and the Yanks are very reluctant to Import Chinese parts.
C: The CNCRP R&P is US made so fits with above.
D: They have never used ball-screws so they don't know the difference in performance and smoothness ball-screws make.
My advise is just that "Advise" take it or leave it but I know thru experience with R&P that Nema23 motors with heavy Gantry is recipe for trouble if your wanting high feed rates.
Yes I know Nema 34 will handle heavy gantry ok and that heavy helps with cutting but Heavy and high feed rates is a completely different issue.!
Combine this with 3D work which requires Small fast direction changes and this issue becomes worse.
Now the difference between R&P and ball-screws is several.
Ball-screws are much more efficient so don't require has much power to turn, typical efficiency for Balscrew is 90%+ were R&P is 60% or lower.
Ball-screws have much lower backlash so are far more accurate and repeatable. R&P is quite high backlash and not easy or cheap to make real antiback lash using correct pinions.
R&P resolution is much lower and to get higher resolution requires at least 3:1 gearing this in turn means steppers need to spin fast and has you may or may not know torque drops off fast at higher speeds on steppers and even more so on Nema 34 motors unless running really high voltage.
R&P is noisy and needs much more maintenance and protection from chips etc.
Ball-screws give a silky smooth action where has R&P is in comparison a clunky action so this does translate back into the cutter at some level.!!. . . For general wood working then this is fine and doesn't get noticed but if your wanting high quality finish or high detail then you will see a enough difference compared to ball-screw machine.
Again just My opinion and you choose to take my advise or not.? . . . . But let me just say go try to find some one who has experience of Both and ask which they would choose for a machine this size, weight and with your requirements.?? . . . . I know the answer because I've give it you.!!
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Re: Sturdy and Fast all Steel CNC , my first build
OK,
I get it. I appreciate the help.
Then what would be your exact recommendation?
Drivers, breakout board, nema 23 motors , PSU combination in combination with which ball screws?
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Re: Sturdy and Fast all Steel CNC , my first build
Quote:
Originally Posted by
silyavski
OK,
I get it. I appreciate the help.
Then what would be your exact recommendation?
Drivers, breakout board, nema 23 motors , PSU combination in combination with which ball screws?
Ok for this size and with Gantry upto 70-80KG.
80V Digital drives and recommend Leadshine AM882
3Nm nema 23 motors like these SY60STH88-3008BF
70Vdc PSU preferably unregulated toroidal with correct amperage for all motors.
BOB recommendation is difficult because the one I'd recommend and think is by far the best is PMDX 126 but it's expensive. PMDX.COM - Products for CNC and motion control applications
The next I'd recommend and use often so know are OK boards is this one. OPPB but it's not in the same league has PMDX.
Ball-screws would be 10mm pitch and 16mm Dia for X & Y axis with 5m pitch 16mm dia. Motors would connect to them using 15mm HTD timing belts and pulleys with 1:1 ratio. This lessens resonance which helps on a steel framed machine and it's much more flexible if you ever want better resolution or higher speed has it's easy to apply a ratio with simple pulley change.
20mm Dia 10mm pitch could be used but really not required at this length and would be over kill, would also restrict performance not increase due to extra inertia of larger screw and ballnut.
All the above I've used on several steel framed machines with gantry's approaching 80Kg so know they work.!!
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Re: Sturdy and Fast all Steel CNC , my first build
Quote:
Originally Posted by
JAZZCNC
80V Digital drives and recommend Leadshine AM882
I see that these get more popular here than the geckos. I read some threads here on the forum. I will go with them
Quote:
Originally Posted by
JAZZCNC
I had my eye on these as a substitute for the ones that i had to buy from abroad and pay duty. I will look deeper in the specs, but most probably will order them through Zappautomation.
Quote:
Originally Posted by
JAZZCNC
70Vdc PSU preferably unregulated toroidal with correct amperage for all motors.
No idea for this one. I should educate my self how to calculate this amperage and from where to get the transformer.
Quote:
Originally Posted by
JAZZCNC
I was looking into this one. For sure i need a board with 2 LPT connections as i need more ports for communicating with the VFD, turning on mist and vaccum and
On my actual small machine i have trip signals from the VFD and power detection which are very handy in real life. And a second BOb af course. So that BOB wins. Actually its not so expensive for what it offers. I spend more money on my 2 boards.
Quote:
Originally Posted by
JAZZCNC
Ball-screws would be 10mm pitch and 16mm Dia for X & Y axis with 5m pitch 16mm dia. Motors would connect to them using 15mm HTD timing belts and pulleys with 1:1 ratio. This lessens resonance which helps on a steel framed machine and it's much more flexible if you ever want better resolution or higher speed has it's easy to apply a ratio with simple pulley change.
20mm Dia 10mm pitch could be used but really not required at this length and would be over kill, would also restrict performance not increase due to extra inertia of larger screw and ballnut.
All the above I've used on several steel framed machines with gantry's approaching 80Kg so know they work.!!
Sorry, i dont understand you:gorilla:
1. 1610 for long axis that moves gantry and 1605 for the gantry / that moves Z/ and 1605 for the z, correct?
2. I buy belts from Belting online. Should i use the minimum sized belt pulley or go a bit bigger for the size of belt i mean? What is the typical size? I cant seem to find the sheet i used for calculating belts. I remember the AT was stronger but a kind of harder. Obviously either way it should be pitch 5, otherwise i have to go with bigger pulleys
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Re: Sturdy and Fast all Steel CNC , my first build
Quote:
Originally Posted by
silyavski
No idea for this one. I should educate my self how to calculate this amperage and from where to get the transformer.
Will PM you about this has it's easy misunderstood and don't want others reading and not understanding properly so getting into trouble blowing stuff up and electrocuting them selfs.!!!!!
Quote:
Originally Posted by
silyavski
Sorry, i dont understand you:gorilla:
1. 1610 for long axis that moves gantry and 1605 for the gantry / that moves Z/ and 1605 for the z, correct?
No 1610 for Long X Axis and Gantry Y Axis (moves Z).
Then 1605 for Z axis (UP/DOWN)
Quote:
Originally Posted by
silyavski
2. I buy belts from Belting online. Should i use the minimum sized belt pulley or go a bit bigger for the size of belt i mean? What is the typical size? I cant seem to find the sheet i used for calculating belts. I remember the AT was stronger but a kind of harder. Obviously either way it should be pitch 5, otherwise i have to go with bigger pulleys
Don't go less than 18 teeth and I always use 20 teeth has the belt engages pulley better giving better wear.
Don't use less than 15mm wide belts and I find 15mm is perfect size. 20 or 25mm is overkill and wasted money.
HTD is the preferred belt type for it's profile but don't think it would make a big difference here anyway has the belts are only short and not under much stress or heavy loads.
Yes 5mm pitch.
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Re: Sturdy and Fast all Steel CNC , my first build
After some fast brainstorm i decided on the CNC4PC breakoutboard 23 coupled with solid state relay board. This board seems more perfect for me:
1.I have my spindle control board from him and the support was great
2. All IC are mounted for easy removal without soldering / this is a big deal, i have repaired breakout boards in the past /
3. All necessary functions and really no extra ones that i dont need and would pay for choosing other boards
4. Better priced than the PMDX 126. When i started adding the spindle control/ not integrated/ ,relays, inputs, outputs, cables and so, the price jumped a lot
5. Some extra jumpers and functions i like
6. Straight out from the box 2 ports BOB with most possible inputs and outputs
Soon will start showing you packets :kiwi-fruit:
Thanks again to Dean/ JazzCNC/, now i know quite more than yesterday:monkey:
Tomorrow will redraw the design for the ball screws.
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Re: Sturdy and Fast all Steel CNC , my first build
Erm.!!! . . . Arturo's stuff is ok but it's no where near has good or well built has PMDX boards.!
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Re: Sturdy and Fast all Steel CNC , my first build
Quote:
Originally Posted by
JAZZCNC
Erm.!!! . . . Arturo's stuff is ok but it's no where near has good or well built has PMDX boards.!
He he he, maybe not but i have been with faulty breakout board and had to wait a month for an exchange. The easily removable IC is a feature that living here in Spain is a must.
the local electronic genius has work for 3 months ahead. And i am not into electronics repair really. Sometimes simpler is better.
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Re: Sturdy and Fast all Steel CNC , my first build
Today after whole day drawing, considering, redrawing, considering... designed the ball screw assembly on Y/ the long axis that moves the gantry/.
I wanted it sturdy, compact, at the right place and most of all easy to rectify and assemble. Following step by step. Still have not figured the belt length, so a minor correction maybe tomorrow. Other challenge was how to keep the working distance at maximum and at the same time ball screw length minimal.
Designed the hard stops with threaded holes for proximity sensors. A bit overbuild but for sure there will be crashes as the guy is a new to CNC.
Some pictures. Have to finish the design this weekend in order to buy the rails, ball screws and order the laser cut pieces.
Attachment 9753 Attachment 9754 Attachment 9755 Attachment 9756
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Re: Sturdy and Fast all Steel CNC , my first build
I don't really understand why the spindle motor is sitting so far below the gantry?
The maximum depth of cut is usually the longest tool that you can fit.
If this to engrave the top of a large object, to clear hold down fixings or what?
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Re: Sturdy and Fast all Steel CNC , my first build
Isn't it more a case of the gantry being positioned high, rather than the spindle being low?
If the bottom of the gantry was level with the top of the x-axis it wouldn't be anywhere near as bad?
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Re: Sturdy and Fast all Steel CNC , my first build
Hi,
as i mentioned before but maybe you missed it, this machine exclusively will be used for 3D jobs most of them in the 140mm-170mm height region. Not for lettering, woodworking or similar.
The guy is doing model yacht building. So shapes would be very strange
So the Z that enters the zone below the gantry should be thin, as not to touch the other parts of the model while the bit is routing deep below hollowing something.
Check my picture and will see for yourself what i mean. Its a specific 3D job machine. I don't believe that reinforced 20mm steel plate for the spindle with 10mm ribs is flimsy as you suggest.
If you have any other ideas i am open to suggestions. Point me to a better solution and i will change the design.
Attachment 9759
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Re: Sturdy and Fast all Steel CNC , my first build
in my opinion with so wide Z axis plates you just wasting a lot of material and travel in Y axis direction.,
with 20mm profiled rails you can do Z axis on 160mm wide plate, and extend travel in Y direction, or just save matirial in all you built.
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Re: Sturdy and Fast all Steel CNC , my first build
Quote:
Originally Posted by
Gytis
in my opinion with so wide Z axis plates you just wasting a lot of material and travel in Y axis direction.,
with 20mm profiled rails you can do Z axis on 160mm wide plate, and extend travel in Y direction, or just save matirial in all you built.
Hi,
you are quite right. However let me explain please. 10cm more of rail on both sides+10cm more of screw+10cm more of steel profile=no more than 60 euro, which is irrelevant in this build. If we look into KG , they are 5-6 kg more on the gantry
However an ATC is very expensive. And is quite necessary for 3D jobs. Should the need arise to upgrade, for the mere cost of 2 more short supported rails and bearings+another chinese spindle i can mount double Z axis with minor modifications and most importantly without compromising the work dimensions. One spindle will rough the other will detail and finish.
I mean, there also some other points of the design that are done with some things in mind. Its not a general hobby machine.
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Re: Sturdy and Fast all Steel CNC , my first build
After some tinkering i woke up that i am not making the CNC for myself and that i am overbuilding it too much. And overthinking it about the eventual future. Went to the local metal shop and checked the profiles. There was 140x80 profile that seemed quite good, so instead of searching for the 180x80, i sat down and redesigned everything, it was fast though taking away things. Changed the profile sizes, took away the reinforcing plates on the gantry, though i left place if i later decide there are vibrations. redesigned the Z narrower and so on. The benefit is that the profile enters the magic 6m number, as they sell it by the 6m.
So following your advice i finished with smaller and lighter gantry, like 30kg, shortened it and now everything is exactly as it should be, no over sized stuff in my opinion. 1000x400x170mm working area, as wanted by the guy.
What do you think?
Attachment 9764Attachment 9765Attachment 9766Attachment 9767Attachment 9768
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Re: Sturdy and Fast all Steel CNC , my first build
Quote:
Originally Posted by
silyavski
What do you think?
Couple of things.!! . . .The Z axis is wrong and your weakening not making stronger.? The spindle hanging down like that in conjunction with rail/bearing setup is a constant length lever at any Z extension.
It won't allow any better clearance when cutting has the Tool length mostly dictates this and your spindle support plate will still catch just like the bottom of Z axis would.
Much better option IMO would be to flip the rail and bearing setup so you have a variable length lever when extended giving much better strength and just build a sturdy spindle bracket that allows percentage of the spindle body to extend below Z axis plate.
This extension along with tool length will be give enough clearance for most 3D work. If the guy needs more clearance then better to buy longer tool and cut slower than compromise the machine in all other areas.!!
With the proximity sensors (Or limit switches) because of the small gaps required to work correctly then I wouldn't put them at the ends were they will get run into if crashed. Position them so they get passed by or over this way nothing gets crushed.
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5 Attachment(s)
Re: Sturdy and Fast all Steel CNC , my first build
Quote:
Originally Posted by
JAZZCNC
Couple of things.!! . . .The Z axis is wrong and your weakening not making stronger.? The spindle hanging down like that in conjunction with rail/bearing setup is a constant length lever at any Z extension.
It won't allow any better clearance when cutting has the Tool length mostly dictates this and your spindle support plate will still catch just like the bottom of Z axis would.
Much better option IMO would be to flip the rail and bearing setup so you have a variable length lever when extended giving much better strength and just build a sturdy spindle bracket that allows percentage of the spindle body to extend below Z axis plate.
This extension along with tool length will be give enough clearance for most 3D work. If the guy needs more clearance then better to buy longer tool and cut slower than compromise the machine in all other areas.!!
With the proximity sensors (Or limit switches) because of the small gaps required to work correctly then I wouldn't put them at the ends were they will get run into if crashed. Position them so they get passed by or over this way nothing gets crushed.
Thanks guys for the input. I seem to have been missing the obvious.
I redesigned it following the advice. Now things seem better / to me at least :-) / . What about the result? By the way i have bought already the spindle brackets/2/ . I liked the design because can fix them on a guiding plate so if i have to move them its easy to align them.
So now the rails move and the bearing blocks stay at optimal position. If he wants to cut thin material he can fix a 10cm high MDB surfaced table made from a couple of boards glued together so there will be no need to change spindle position at all. And take it off when he likes to do deep jobs.
Can i cut the motor shaft from the back side? Is it enough place for the cables of the motor? See picture. I need to further redesign it a bit otherwise i have to solder it with the motor in place , he he he. Ok, i wouldnt do it so. Just joking.
Attachment 9770Attachment 9771Attachment 9772Attachment 9773Attachment 9774
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Re: Sturdy and Fast all Steel CNC , my first build
If this guy is wanting mainly to do 3D work then I'd also look to make the Front Z axis plate the narrowest and lightest you can make it.
Keep the Y axis bearing spacing wide but bring the Z rails in the most you can get away with and have light narrow front plate.
3D requires fast directional changes and high acceleration so anything to help here will speed up the job.!
Regards the motor access you have enough width and height in that plate to cut an access hole for motor and still not lose any strength, will cut weight too.! . . .Win win.!!
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2 Attachment(s)
Re: Sturdy and Fast all Steel CNC , my first build
Quote:
Originally Posted by
JAZZCNC
If this guy is wanting mainly to do 3D work then I'd also look to make the Front Z axis plate the narrowest and lightest you can make it.
Keep the Y axis bearing spacing wide but bring the Z rails in the most you can get away with and have light narrow front plate.
3D requires fast directional changes and high acceleration so anything to help here will speed up the job.!
Regards the motor access you have enough width and height in that plate to cut an access hole for motor and still not lose any strength, will cut weight too.! . . .Win win.!!
Thanks Dean,
I finished with a 130mm wide fron z plate. It should be enough. I dont believe it can compromise anything, as in my router i have exactly this plate using only one slide with the wide flat rail+ 2 bearing blocks and is ok strong. However i would not like do it like this in this build, cause later i have to play a lot with hole placements and finding screws that could fit under the plate and then aligning it. As i did with mine.
I have another question. When laser cutting, should i do exact holes that hold the plates to the bearing blocks or i should elongate them. Cause how do i know that the rotating nut will fit exactly at that place. Otherwise i will loose some millimeters from the travel. How it is done?
Attachment 9775Attachment 9776
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Re: Sturdy and Fast all Steel CNC , my first build
Hi there,
today worked more on the drawings, mostly lightening things where possible without compromising strength. Starts to look like a cheese. However all holes will be closed with bolted light plastic plates so at the end will be quite dustproof even if its not seen on the drawing.
Received the spindle mount brackets. And made an important decision.
Well the 2 brackets are very nice, especially for the money, but... not the same as on the sellers picture. In fact they are so robust that i will use only one. man, they are big.
The important decision is that until i don't have the ball screws and the Hiwin rails at hand Not to order and laser cut pieces and not do any soldering at all. My design heavily depends on the exact hole placement and the laser cut pieces, because i have at hand a very cheap laser service, so cheap that it would be more costly to than to draw by myself and drill the holes at home from junk steel plate with my flimsy drill. And as i don't have a mill at hand and the service here in Spain is very expensive, laser cut is the way for me. Which gives me quite a freedom in my design.
I need some help with the following because i have no idea at all:
1. Proximity sensors
Ok, i designed a plates for them, there is like 12mmm possibility for adjustment. Will solder the plates /10mm thick/ directly on their places. But..
-How far from the actual x,y,z hard stop ???? / x = moves the z , y=moves the gantry/
-any example of Z proximity switch placement? No idea still how and where to fix them. Of importance is the diode to be visible.
-Homing of the z is up, yes?
2. Drag Cable Chain
The thing still missing from the drawings.
-Judging from my current setup/2 small chains one next to another/ i need 20x50 internal drag cable chain so cooling hoses and cables can pass freely. But... i can not find anywhere what is the radius. Grrrrrrrrr. If somebody has a similar chain and point me to the radius i would be very grateful
3. Motor cables
can somebody point me to per/m good motor cable, shielded, here in EU?
It seems also for the purpose of the chain, i have to lift the machine. Another thing is that i still have not found a good case for the electronics. It has to look really good.
I am starting to thing about raising everything and boxing the electronics inside the machine. I have my small machine at home like this, so i know the all bad points and will avoid them. Believe me there are many. Like when drivers heating from inside, heats my aluminum table that heats the hot glue i use for fixing stuff and everything flows in the air some times when routing... Of course knowing them i can avoid them. By the way vibrations to the components was only once a problem and it revealed a cold weld on the BOB transformer. Nothing more...
Attachment 9904Attachment 9905
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2 Attachment(s)
Re: Sturdy and Fast all Steel CNC , my first build
Waiting for the square rails and ballscrews purchace, made me play again with the design. Decided to stuff all the electronics inside the body. Due to various reasons like avoiding
10 Neutric connectors sticking out at the back, cables, enclosure and so on. mainly because i live at the seaside so connections always give me trouble and i have to glue my connections with hot glue.
Decided also to make the structure from 60x60 4mm at the important places and 3mm at the no so important. But what ever i did i couldn't figure placing diagonals so i finished with rigid square design and 100kg structure. more or less 18meters of steel. I think i overbuild it a bit.
Another decision was to make the bed deep enough so there is no need to change spindle position. Instead a wood bed would be fitted so the spindle works at normal position and only when necessary to remove the wood bed, not move the bed of the machine or anything.
Hope that structure is strong enough, cause tomorrow will order the steel.
Attachment 9945Attachment 9946
If somebody sees something wrong, please tell me until is time, he he.
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Re: Sturdy and Fast all Steel CNC , my first build
Everything ordered including the steel for the structure. Still have not ordered the laser cut parts. Untill i have the rails and ball screws at hand.
And here comes the first major problem. The place where i found the 140x80 profile for the gantry refuses to sell me 1m even they have promised me before. :devilish: . Now i have to buy 6m , or change the design.
At the other place where i would buy the rest of the steel, i found some pieces of 100x100x4 box profile. And generally they will sell me everything cheaper and help me in their machine shop. So now i am contemplating soldering 2 pieces of 100x100 and making the gantry 100x200mm. That would change the design of the gantry widening 2cm, one at each side and making it higher by 6 cm.
What is your opinion about this change? The ball screws will be further 2 cm from the z plate. And the upper bearing slides and rail will go 6 cm higher.:stupid:
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3 Attachment(s)
Re: Sturdy and Fast all Steel CNC , my first build
No body says nothing, may be the thread is not so interesting as it seems to me or i am doing it right :hysterical:
Soon will make it more interesting with pictures of the process. Now everything is ordered including the steel profile. Will have to pick it tomorrow and solder it this weekend.
At the end i used only 100x100x3mm steel box for everything. The 4mm seemed very heavy and overkill for the 0.8kw spindle .
I still have doubts for the threads on the rails so most possibly will solder additional plates for the threads of the rails. Anyways they will be covered by epoxy.
Here is the final design , its lighter and stronger than the 60x60x4 and also another point is that less cutting and soldering is needed.
400x1000 x Z 170/up to 200/ working area, gantry ~35-40kg with everything mounted, profile structure and gantry with plates = ~ 100kg
Attachment 10223
Attachment 10221
Attachment 10222
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Re: Sturdy and Fast all Steel CNC , my first build
Quote:
Originally Posted by
silyavski
No body says nothing, may be the thread is not so interesting as it seems to me or i am doing it right :hysterical:
Hi silyavski,
There may be another explanation and that is maybe something wrong with the forum...... I have been lurking recently and don't recall your post #25? Although individual posts may sometimes get lost in a rush of posts!
Cheers,
Andy
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Re: Sturdy and Fast all Steel CNC , my first build
Quote:
Originally Posted by
silyavski
No body says nothing, may be the thread is not so interesting as it seems to me or i am doing it right :hysterical
I didn't see these post's either.!
Anyway it's looking good. The 3mm wall thickness will be fine for the rails holes but don't drill them until you have epoxy on the rails. If you do it before then you'll create your self more work.
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Re: Sturdy and Fast all Steel CNC , my first build
This provoked my first post here...
I'm in the middle of my own build (quite similar to yours) and I'm using 100x100x10 so I'd throw in a few words... Don't overlook the edge radius of your SHS. I got unpleasantly surprised when I was supplied with 100x100 SHS that has 35mm (or perhaps even more) diameter at edges... I was counting with 25mm diameter I found in tables of SHS somewhere but the supplied steel was cold rolled with much larger edge radius. My rails will be right at the edge of square so I added thick plate on top of SHS to support the rails. You may not have this problem with 3mm wall but I'd check at the supplier and verify the design with that in mind.
Good luck!
Adrian
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Re: Sturdy and Fast all Steel CNC , my first build
Quote:
Originally Posted by
HoGo
Don't overlook the edge radius of your SHS. I got unpleasantly surprised when I was supplied with 100x100 SHS that has 35mm (or perhaps even more) diameter at edges... I was counting with 25mm diameter I found in tables of SHS somewhere but the supplied steel was cold rolled with much larger edge radius.
That 35mm is very large Diameter and your correct it should be more like 25mm, I have some 200x100x10 here and that is only 22mm Dia. I would have took it back.!!
The Dia on 100 x 100 x 3 will be roughly 8mm, I've got some 150 x 150 x 5 here and the Dia is 12-14mm.
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Re: Sturdy and Fast all Steel CNC , my first build
Thanks for the advice. I just came from the metal shop, but they still have not cut it. However the profile seemed normal squarish, nothing unusual, so i believe that will not be a problem.
I wonder guys what are you constructing with 100x100x10 :loyal:?
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Re: Sturdy and Fast all Steel CNC , my first build
Quote:
Originally Posted by
silyavski
I wonder guys what are you constructing with 100x100x10 :loyal:?
My case It's actually 200x100x10 with front face ground for rails and it will be Fixed gantry for my new DIY-VMC .!!!
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3 Attachment(s)
Re: Sturdy and Fast all Steel CNC , my first build
Quote:
Originally Posted by
silyavski
I wonder guys what are you constructing with 100x100x10 :loyal:?
This:
Attachment 10231Attachment 10232Attachment 10233
Actually the table and gantry are welded and waiting for milling for rails. So far we are at roughly 400kg, finished machine will be just hair under 600kgs. :smile:
Adrian
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Re: Sturdy and Fast all Steel CNC , my first build
Quote:
Originally Posted by
HoGo
Hi Adrian,
i couldn't help but notice, your gantry is only supported by 1 side plates at each end? Wouldn't it need something stronger, like my design? As profile like support at the sides is stronger from even a thick plate i believe. There is a calculator Excel sheet somewhere here on the forum.
Your table structure looks great, and i have given a lot of thought how to make gantry similar to yours, it looks great also.
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Re: Sturdy and Fast all Steel CNC , my first build
The gantry sits directly on the 20mm plates that will hold the rotary nuts, to which another 22mm thick plates with cars will be mounted. There's no gap there. The sides are 12mm thick steel. So there is direct contact of bottom of gantry ends to rail cars. There is no measurable side to side movement possible other than any play in the rails/cars.
I used 100x100x10 SHS for most of the construction as I had to order two 6m lengths and didn't want to throw away too much. Also one 6m length of 140x80x7 was used for gantry and for two table supports, all was used up almost without waste (supports intentionally placed along the table to create space for extra long 4th axis as we'd like to make some gunstocks in the future).
Adrian
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Re: Sturdy and Fast all Steel CNC , my first build
Quote:
Originally Posted by
JAZZCNC
My case It's actually 200x100x10 with front face ground for rails and it will be Fixed gantry for my new DIY-VMC .!!!
Are you taking orders for it yet? :thumsup:
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Re: Sturdy and Fast all Steel CNC , my first build
Quote:
Originally Posted by
HoGo
The gantry sits directly on the 20mm plates that will hold the rotary nuts, to which another 22mm thick plates with cars will be mounted. There's no gap there. The sides are 12mm thick steel. So there is direct contact of bottom of gantry ends to rail cars. There is no measurable side to side movement possible other than any play in the rails/cars.
I used 100x100x10 SHS for most of the construction as I had to order two 6m lengths and didn't want to throw away too much. Also one 6m length of 140x80x7 was used for gantry and for two table supports, all was used up almost without waste (supports intentionally placed along the table to create space for extra long 4th axis as we'd like to make some gunstocks in the future).
Adrian
Thanks Adrian! Now i get it. Its not raised. Same with me. Have to think in 6m lengths :-) .
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Re: Sturdy and Fast all Steel CNC , my first build
I just realised the pics I posted were somewhat outdated. In the final version I moved the tabs holding rotating nuts/servos of X axis to the rear and turned them 180 degrees so the pulleys are just at the rear plane of gantry. This was done to make possible to add another pulleys so I can belt the two sides together with one long belt. There are schools of thought (especially on our local CNC forum) that they'd better be tied together so if one side will stall or not work properly the gantry won't damage the rails. I believe that this is not necessary as servos have quite reliable feedback and one stepper just wouldn't have enough torgue to damage rails and the other side will stall within few steps from the first side.
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Re: Sturdy and Fast all Steel CNC , my first build
Quote:
Originally Posted by
HoGo
I just realised the pics I posted were somewhat outdated. In the final version I moved the tabs holding rotating nuts/servos of X axis to the rear and turned them 180 degrees so the pulleys are just at the rear plane of gantry. This was done to make possible to add another pulleys so I can belt the two sides together with one long belt. There are schools of thought (especially on our local CNC forum) that they'd better be tied together so if one side will stall or not work properly the gantry won't damage the rails. I believe that this is not necessary as servos have quite reliable feedback and one stepper just wouldn't have enough torgue to damage rails and the other side will stall within few steps from the first side.
I believe the same. Moreover i believe this belt being so long is not a good idea if the expectation is to route aluminum, but that's me. I have a small belt driven machine and on it have the motor steps adjusted for wood and for aluminum differently, to compensate belt stretch. Dont know how that be if using big fat belt 25mm wide. Maybe will not stretch if pre loaded/pre tightened correctly.
Anyways the steppers just stall. Who knows what can happen with servos if stalled, i have no idea. Still not in that league.
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10 Attachment(s)
Re: Sturdy and Fast all Steel CNC , my first build
At the end i have the profile cut, had to help the guys from the metal shop otherwise it would be next week.
Time to make some sparks and test my recently acquired new toys:
-3 in one plasma cutter, pulse tig , stick 200A
-Mig 250A
I decided to go with the MIG even as it seems that i do better looking welds with the arc welder. Yes, its strange but is so. Would have Tig-ed it but still no Argon bottle. maybe the Mig welds are more difficult to me due to the fact that i use beer gas. The penetration is perfect, before some days welded 10mm pieces without any problem. I was saving quite some time for the 2 machines, the combi cost 470 euro and the MIg 330eur with shipping to Spain. Both from fleabay. Needless to say the Mig was a great deal for the money.
I was a little worried because my welding is 1h practice at home and watching a lot of videos. But it went extremely well. It seems i weld quite well, the only thing is that my head is not shaped for welding helmets, whatever i did it could not fit properly
Attachment 10258
First did the gantry. Spot welded it, let it cool, then started short welds, then turn, then weld, then let it cool. I used my IR remote thermometer to monitor the temperature of the gantry to not pass 60C. So at the end i welded it quite precisely in fact, without twisting. However i was quite tempted to do a perfectly looking straight weld from one side to the other :orange:, but followed the correct procedure.
Attachment 10259
Then decided to weld the left and right sides and later connect them. The guys at the metal shop told me first to weld the bead square and then the rest. However i decided what i felt was better, for the purpose of easier adjustment . I decided to weld it precisely, like i would not use epoxy. Wanted to check if i am being able to do this.
Attachment 10260
Please don't laugh at my welds, at least they are really penetrating. The spatter is from the gas i believe.
Attachment 10261
Ground the welds where the bed profiles go. Now the thing is that i have only 2 large clamps. I tightened slightly all from both sides on my new acquisition, the welding leg supports i acquired exchanging a vacuum pump for them. using a square and a plastic head hammer started playing around until i finished with square bed on one and the same plane.
Attachment 10262
To make sure the bead is on the same plane i used Bosch alu profile as my Din 874 straight edge is still travelling
Attachment 10263
Attachment 10264
That the bed is square and is on one plane dos not mean that the most important part-the rail support profile is on the same plane, even if you welded properly.
Attachment 10265
I would epoxy it later, but i tried to make it perfect, so i decided to spot weld only from the upper sides, cause as i said i have only 2 large clamps. later would take off the clamps and adjust the squareness and being in one plane of the rails supports. As the bed is spot welded only from the top, Using the clamps end by end i leveled the rails supports. Then soldered.
Attachment 10266
Then became dark, and i -tired but happy. I know, its not a big deal, but for me-yes, cause i bought 2 welders and started a build without knowing if i can weld or not. So, now i relaxed a bit. The machine frame stays in front of my small workshop, cause now i can not lift it alone. It seems extremely rigid, much more than i expected. When i am finished, will measure the flex from 90kg on the bed /me/ . The gantry seems indestructible. I underestimated the need for hard stops. back to my first design. Monday will go and by some U profile. I thought of stopping it with bolt. No way, it should be something very strong.
Attachment 10267