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6 Attachment(s)
Small rigid router - Design advise needed
Hi, this is my first stab at the design after having a good look at some of the great builds here. Any advice or comments would be greatly appreciated! Requirements for the machine as following
Exclusively for machining aluminium
Cutting area: 600mm x 450mm x 150mm.
Speed is not a great issue
I got hiwin HGR15 rails and blocks and Chinese 1605 ballskrews and ballnuts so I'll use those.
Since aluminium is not cheap here I'm going for a welded steel design and then alu on Z because there's a bit of machining required there.
Some basic dimensions for reference.
Distance between gantry side rails: 800mm
Distance between top and bottom rails on gantry: 300mm
Z plate with 250mm
Box section used is 160x80x3mm and 120x80x3mm
10mm 10mm sheet for flat parts to be laser cut
Y carrage and Z assembly is 25mm alu with a 10mm plate at the back
A few questions:
Will the long belts (+-650mm on Z and 550mm on Y) cause any issues? HTD 5mm pitch x 15mm width with 20tooth pulleys
The gantry is very rigid and HEAVY but I'm worried about ressonance. Can one fill it with something that's not going to add a lot more weight that will help with resonance.
Does the 3 rails on the gantry make sense? I've got 1 on top and two at the bottom.
Please comment if you spot anything that's not going to work or things I can improve without adding major cost
http://www.mycncuk.com/attachment.ph...id=13201&stc=1http://www.mycncuk.com/attachment.ph...id=13202&stc=1http://www.mycncuk.com/attachment.ph...id=13203&stc=1http://www.mycncuk.com/attachment.ph...id=13204&stc=1http://www.mycncuk.com/attachment.ph...id=13205&stc=1
http://www.mycncuk.com/attachment.ph...id=13206&stc=1
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Re: Small rigid router - Design advise needed
You could shorten the z belt by moving the motor and turning it the other way up so that the pulley if facing down. ..Clive
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Re: Small rigid router - Design advise needed
Thanks Clive, I'll give that a go then I can also move my Y stepper up a little bit to shorten that belt.
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Re: Small rigid router - Design advise needed
ja ja wat se jy :P
why even go with belts ? are you going to have a step down ratio ?
i wouldnt bother with the 3rd rail, i think it will just make it harder to clock up ...
what or how are the two bottom rectangle tubes fastened ?
looking good :D
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Re: Small rigid router - Design advise needed
Looks pretty good but to make life easier later I would draw in your energy chain, drag chain, whatever you call it because it could affect some aspects of the design such as , mounting brackets, length of travel in X direction. Also consider limit switches and homing switches locations.
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Re: Small rigid router - Design advise needed
:-)
No, its just 1:1 ratio. My understanding is that belt drive will make the machine a little smoother. X and Y would be possible to do direct drive but Z will be difficult as I'm trying to keep it as flat as possible.
Not sure but I'm thinking of welding on tabs or a piece of flat bar on both sides that will allow me to bolt it to the table.
Quote:
Originally Posted by
Blackrat
ja ja wat se jy :P
why even go with belts ? are you going to have a step down ratio ?
i wouldnt bother with the 3rd rail, i think it will just make it harder to clock up ...
what or how are the two bottom rectangle tubes fastened ?
looking good :D
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Re: Small rigid router - Design advise needed
Thanks for the advice EddyCurrent. I will start adding those as I can see it might be an issue with the design as it is now, especially the drag chain running on or behind the gantry.
Quote:
Originally Posted by
EddyCurrent
Looks pretty good but to make life easier later I would draw in your energy chain, drag chain, whatever you call it because it could affect some aspects of the design such as , mounting brackets, length of travel in X direction. Also consider limit switches and homing switches locations.
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Re: Small rigid router - Design advise needed
belts aint gonna make it any smoother .... id run a coupler on the two axis' , so much easier and cheaper
im not quite with you on bolting it to a table ? you HAVE to join either sides , no ways you going to cut ally decently if they are seperate from each other, not to mention the nightmare of trying to get them parallel by clamping to a table
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Re: Small rigid router - Design advise needed
I am no expert but if you follow this forum and take notice of the Master's on here, coupling with belts helps to eliminate resonance which can stop a motor dead in its tracks. Try running a stepper with a loose mounting to see the effect. ..Clive
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Re: Small rigid router - Design advise needed
Thanks for the feedback Blackrat. I also like the simplicity of direct drive but quite a few people here believe belt-drive is the better route. I don't know how much better?
The table/base will be a very sturdy steel frame so the two sides are build separately but when bolted down they are connected via the base or am I maybe misunderstanding your question. I guess I can also weld them to the table but that won't be much stronger than having several bolts on each side of both or will it? I thought bolting them would make the alignment easier.
Quote:
Originally Posted by
Blackrat
belts aint gonna make it any smoother .... id run a coupler on the two axis' , so much easier and cheaper
im not quite with you on bolting it to a table ? you HAVE to join either sides , no ways you going to cut ally decently if they are seperate from each other, not to mention the nightmare of trying to get them parallel by clamping to a table
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Re: Small rigid router - Design advise needed
With regard to the base, you need to post some drawings I think. With anything, you need good solid foundations to build from.
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Re: Small rigid router - Design advise needed
Quote:
Originally Posted by
mitchejc
The table/base will be a very sturdy steel frame so the two sides are build separately but when bolted down they are connected via the base
thats not going to work
no ways you gonna bolt it together so that the rails come out within a decent tolerance ....
have a read about epoxy leveling a frame if you havnt already ?
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Re: Small rigid router - Design advise needed
Yep, you are right, I'll do the drawing for the base and post it as its obviously an integral part of the design.
Quote:
Originally Posted by
EddyCurrent
With regard to the base, you need to post some drawings I think. With anything, you need good solid foundations to build from.
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Re: Small rigid router - Design advise needed
I'll try and get the drawings done, but the picture I have in mind is basically a 4 legged steel tube structure made from 80x80 tubing with lots of support under the table and space inside where I can sandbag the whole thing to add lots of weight to the base. I then epoxy level the top of the steel base to get that flat, bolt 2 layers of good quality birch ply + a 5mm steel sheet on top. Then bolt the gantry sides to that surface and epoxy level them before the rails go on. Does it sound practical or are there an easier way to build a sturdy base. I started off with the idea to do a concrete slab on top of a steel structure but there's just to many issues with that approach.
Quote:
Originally Posted by
Blackrat
thats not going to work
no ways you gonna bolt it together so that the rails come out within a decent tolerance ....
have a read about epoxy leveling a frame if you havnt already ?
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2 Attachment(s)
Re: Small rigid router - Design advise needed
Ok this is roughly what I have in mind for the base. Idea is epoxy level the top of the base just to get it +- flat and level. Then put 2 layers of 16mm sealed birch ply on top and then a 5mm steel plate and secure that to the base with bolts. Apart from using bolts I really don't see another option of how to secure the machine to the table? I'm referring to the red parts in the second picture. I really don't want that to be the weak point so I'm open to suggestions. Am I approaching this the wrong way to wanting to build the router and base separately? Any advice would be greatly appreciated!
Attachment 13218Attachment 13219
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Re: Small rigid router - Design advise needed
IMHO:
- no need for such a beast table.
Use 100x100x4 or 100x100x3 and make something similar like i did, worked quite well. Its simpler, cheaper and easier to make. At the back you can see the same design but with legs. See post #53
-Z belt length bothers me. See how i did it. post #109
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Re: Small rigid router - Design advise needed
Quote:
Originally Posted by
Blackrat
thats not going to work
no ways you gonna bolt it together so that the rails come out within a decent tolerance ....
have a read about epoxy leveling a frame if you havnt already ?
Depends how it's done. Epoxy leveling isn't the be all and end all solution. I've said this many many times but for a good DIY machine you need to build in as many oppertunity's for adjustment as possible and bolting allows plenty of scope for shimming etc to get machine accurate.
If done correctly then it's actually better than epoxy because you can fine tune to very high tolerence.! Only thing is it takes much more time and patience.
Quote:
Originally Posted by
Blackrat
belts aint gonna make it any smoother .... id run a coupler on the two axis' , so much easier and cheaper
Actually can make a huge difference esp on all steel machine that's running analog drives with limited resonance handling. This is actually the main reason to use Belts and the ratio option and flexabilty is just a bonus.
Often folks running direct drive don't realise they have resonance problems and just accept that the speeds and performance they are getting is just the max level they can tune to or achive from there motor/drive setup. When often the reality is that the same motors/drives when run on belts and unaffected by resonance will achieve much higher and smoother performance.
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Re: Small rigid router - Design advise needed
@ silyavski
Thank very much for the reply, I was hoping you would have a look at my design. Your build really inspired me to go the metal route!
Point 1: Agree 100%. After calculating the cost for that brute of a table I realized I have to scale it down a bit so I'll do that
Point 2: The belt length is also bothering me. I really like the way you did yours but I have a bit of a problem because I already have a 350mm long ball skrew for my z and also my steppers which are very long so there's just no way I can do it the same as you did yours. My compromise at this stage is to make the gantry top narrower to move the stepper closer to the ballskrew or go with the long 650mm belt. Which one do you think is the better option? I think my wife will poison me if one more parcel with cnc parts gets delivered here so getting a longer ballskrew is not an option :friendly_wink:
Quote:
Originally Posted by
silyavski
IMHO:
- no need for such a beast table.
Use 100x100x4 or 100x100x3 and make something similar like i did, worked quite well. Its simpler, cheaper and easier to make. At the back you can see the same design but with legs. See post
#53
-Z belt length bothers me. See how i did it. post
#109
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Re: Small rigid router - Design advise needed
@JAZZCNC
Thanks for the great input. I'm going for the belt option. I think I got decent steppers and drivers but I'll do anything that might deduce resonance and I like the possibilities that the belts give e.g. change the ratio if I needed. Not sure with a ballskrew system but I know from first hand experience with rack an pinion that belts also offer little bit of safety margin with strong steppers and would jump teeth or snap when things go horribly wrong.
I've thought long about Blackrat's suggestion not to bolt the sides down but there's much weaker points in the design so I'm pretty sure that not the weakest link. The other thing is I'm really a novice welder so I'm not very confident I'll be able to build the base and gantry sides as one unit to any reasonable tolerances. With the bolt on plan I do limit that factor a little as I have the opportunity to shim an adjust a little like you suggested.
I wish I could hear silyaski machine take an aggressive cut into a piece of alu then maybe I can put my mind at rest about the steel structure resonance :-) Has anybody tried to fill the steel sections of the gantry etc with high density polyurethane foam and would that make any difference with resonance? I'm referring to the two part stuff that can be pored thru relatively small holes and then it foams into a plastic like solid to fill the entire void.
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3 Attachment(s)
Re: Small rigid router - Design advise needed
Quote:
Originally Posted by
mitchejc
@
silyavski
oint 2: The belt length is also bothering me. I really like the way you did yours but I have a bit of a problem because I already have a 350mm long ball skrew for my z and also my steppers which are very long so there's just no way I can do it the same as you did yours. My compromise at this stage is to make the gantry top narrower to move the stepper closer to the ballskrew or go with the long 650mm belt. Which one do you think is the better option? I think my wife will poison me if one more parcel with cnc parts gets delivered here so getting a longer ballskrew is not an option :friendly_wink:
Then flip the motor. Look at the z i am doing right now.
Note that:
-the plate is reinforced against vibration with the small triangular pieces
-longer towards the front plate - to provide dust protection
-longer towards the back - to mount the cable chain there
Attachment 13290Attachment 13291Attachment 13292
Quote:
Originally Posted by
mitchejc
I wish I could hear silyaski machine take an aggressive cut into a piece of alu then maybe I can put my mind at rest about the steel structure resonance :-) Has anybody tried to fill the steel sections of the gantry etc with high density polyurethane foam and would that make any difference with resonance? I'm referring to the two part stuff that can be pored thru relatively small holes and then it foams into a plastic like solid to fill the entire void.
Dont worry about that. It does not vibrate at all. I see your design ok. Not quite the expert though. use common sense and reinforce with 10mm steel rib plates where necessary against bend and twist
Important part of my design are the stair like pieces which reinforce in all directions and don't transmit resonance. To understand better what i am saying, this design is better than just sticking two profiles together.
Split and conquer! That's how you fight resonance.
Soon will make some aluminum pieces for my machine i am building right now, so will show a video about the aluminum, though my friends machine/ the yellow one from the build / has only 0.8kw spindle so it could not be appreciated very much, but there is no resonance, glass like finish.
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Re: Small rigid router - Design advise needed
Just saw your gantry. what size profile you use?
I don't like that back plate there, only adds weight and no gain at all against twist nor against bend in the middle.
Look how i do it on my build right now. Profile 100x100x4 up and down and in between 60x60x3 or 60x60x4 , 2 pieces soldered together, . The Z is 3mm from gantry. Just welded today my 1800mm gantry and confirm that is stiff as it could be. Will measure the bend tomorrow.
Attachment 13293Attachment 13294
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1 Attachment(s)
Re: Small rigid router - Design advise needed
The top and bottom is 160x80x3 each with a 120x80x3 between them as per below picture. The main benefit is a very simple construction and less parts but the down side is those three sections are quite heavy. Because I'll have to buy 6m of each section the plan was to use the same for the sides that bolt to the table.
I agree the back plate does not offer much apart from completing the box instead of just a U so it might stiffen things a little but its probably not worth the weight and alu cost. Wow I like your gantry and ESPECIALLY the new Z design! Now you got me going back to the drawing board with mine :-) Will you please send me the link to the thread with your new design.
Attachment 13295
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1 Attachment(s)
Re: Small rigid router - Design advise needed
Post #56
Ignore the double ball screw, i will mount at least once a vibrating hammer so that's why. Same goes with the triple bearing blocks. 2 are enough. The 2 square bars on the Z plate can easily be substituted by structure of 20mm plate, but i don't have the time to fiddle with it so i will use solid alu bars.
Today just soldered many things. Still no time to update the thread, but one of the things i most like about this design are the gantry legs, save some money on plates, cutting and welding. Cheap profile i mean instead of laser cut plates. As i changed some bits of the design, the gantry legs will have a plate below slightly larger or access hole for mounting the bearing blocks. But i wanted it strong left right, that's the change from the initial plan. look below:
Attachment 13297
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Re: Small rigid router - Design advise needed
Thanks for taking the time to reply. I really like your design and I can see you put a lot of thinking into making the construction easier without compromising strength. The simplicity of the two solid bars on the top and bottom is a great plan. I'm going to keep a very keen eye on your build to see how you do things. Time for me to start changing my drawing to incorporate some of your new ideas. The only thing I will do different on mine is to not have the rotating ball nuts on the x. Not because I don't think its a good idea but its my first serious build and I'll rather avoid that bit of complexity and go for the stationary x motors on mine.
How are you mounting the spindle inside the z box? Are you making a custom mount or will you just be modifying those standard cast spindle mounts?
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6 Attachment(s)
Re: Small rigid router - Design advise needed
Quote:
Originally Posted by
mitchejc
How are you mounting the spindle inside the z box? Are you making a custom mount or will you just be modifying those standard cast spindle mounts?
Attachment 13300 Attachment 13301
Quote:
Originally Posted by
mitchejc
The simplicity of the two solid bars on the top and bottom is a great plan.
if speaking about the gantry, today while soldering changed the idea. As it was impossible to weld it well from all sides. So did not use the square tubing for support. Just made more ribs. Anyway i have bought 6m for the 2 plates, so i had enough of it. Instead used the square tube pieces/60x60/ to align the ribs. Its ridiculously strong. the gantry i mean. but the welding goes ridiculously slow. Great care should be taken. First spot weld, then short passes, then wait, then short passes... Still have to finish it tomorrow.
Attachment 13302 Attachment 13303Attachment 13304Attachment 13305
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Re: Small rigid router - Design advise needed
Quote:
Originally Posted by
mitchejc
Has anybody tried to fill the steel sections of the gantry etc with high density polyurethane foam and would that make any difference with resonance? I'm referring to the two part stuff that can be pored thru relatively small holes and then it foams into a plastic like solid to fill the entire void.
No it doesn't work very well there's not enough density. The best success i've had is with kiln dried sand. Very cheap and simple with good results.
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Re: Small rigid router - Design advise needed
Thanks for the photo's Sylafski. VERY nice!! That gantry looks extremely solid.
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Re: Small rigid router - Design advise needed
@JazzCNC
Thanks Jazz, the sand makes sense. I'm bit worried about adding more weight to the gantry as I estimate it's already +- 80-90kg Z & spindle included but I guess a 20-30kg of sand is not going to hurt or will it? My plan is to run 8nm easyservos, will that work or do I need to back off a bit on the gantry weight?
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Re: Small rigid router - Design advise needed
hi
Are you going to use servos or motors with encoders, if not, than you should change design for one motor on X but with two screw on each side. Loosing steps issue - big problem when you mill harder stuff like alloy.
I had the same problem - its complicate design, but for long term your gantry always run smoothly, without jamming on one side
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Re: Small rigid router - Design advise needed
Tom, thanks for the advise. Yep, I have EasyServos which are basically steppers with encoders but if I have any issues with racking I'll certainly go the single motor route.
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4 Attachment(s)
Re: Small rigid router - Design advise needed
Thanks for the advice so far. Muchappreciated! Plan is still to build a base with aflat top and then bolt my machine on top of that. I'm basically done building the base and I'll post a few pics soon so its now time to start focusing on the actual machine.
I really had a hard time deciding onthe gantry design. I know the box section designs are proven and works verygreat but if possible I would like to try something a little different with a welded structure made from round tubes, angle section and flat cross supports. Tubes will be sand filled. I'm hoping to get away without epoxy leveling so the idea is to have the X and Y rails sit on 10mm thick ally plates bolted on top of the steel that I can hopefully machine flat and parallel. If that fails I'll go the epoxy route.
Below is what I have in mind. Pleaselet me know if you spot any fundamental issues or things I canimprove. Steel parts are blue and alu parts are grey
http://www.mycncuk.com/attachment.ph...id=13816&stc=1http://www.mycncuk.com/attachment.ph...id=13817&stc=1http://www.mycncuk.com/attachment.ph...id=13818&stc=1
The core of the gantry looks like this consisting of 76mmx5mm round section, 50mmx5mm angle section , 100mmx10mm flat bar and several 10mm and 6mm thick braces
http://www.mycncuk.com/attachment.ph...id=13819&stc=1
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Re: Small rigid router - Design advise needed
What are these 3 small diameter bars along the sides? mounting threaded bars with nuts to hold all together when welding?
What do you want to hear that may be you don't know-beautiful to look at but a waste of material with no further benefit, even worsening some strength points. Unnecessary heavy/plates/ where not needed / table structure/ but nevertheless pleasing to the eye .
What about the orange material, what is it made from? The sides are weaker than box section so if this is weak all will creep.
Basically the "fundamental" issue i see is this:
Instead of strong all supported rails supported by strong all supported steel box structure, supported by itself and gravity on a not so strong table, you are trying to do exactly the opposite- make very strong table, weaker structure and even its weaker semi supported just below the rails themselves. And that for at least 2 times the weight /$$$/ of the material needed.
That is why when i design something i design it like this- bench top, even if its 3x2m steel cnc. Why? Because that's the main structure that will do the job. All else is secondary-serves to lift it to some level or to put something between the floor and the "real structure".
So why not forget all and design a good strong benchtop CNC and then design separate table for it...
When i finished the yellow machine from my first build i said to my self one thing- on the next one i will do all possible to avoid laser cutting and massive laser cut part list and i see here lasercut steel that weights a lot and $$$ to cut.
Plus actually similar sized steel tubes are not stronger or more ridgid than box section:
100x100x4 moment of inertia 236cm4 , torsion inertia 353cm4 Shear modulus/rigidity 36.86cm3
100x4 tube 139cm4 278cm4 55.33cm3
Your mistake here is that yes, 200mm x4 steel tube is much more stronger and rigid than 2 x 100x100x4, but imitating it with 3 tubes and a lot of steel ribs does not do the same job . The questions with 200x4 tube is how to fix the rails and how to deal with overhang/the bulge of the tube/ mantaining at the same time the spread between the rails.
So, box profile structure beats all in simplicity and strength, especially if made stair like with short pieces in perpendicular direction. Sides and gantry.
Please excuse me about the colors,but it helps me better express my thoughts and organize them. I tried not to make all in red and bold :hysterical:
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Re: Small rigid router - Design advise needed
Have you priced up laser cutting yet ?
One large dia tube is going to be much stiffer
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Re: Small rigid router - Design advise needed
Silyavski, thanks for the detailed reply, I do value your input. Like many others on here I'm no mechanical engineer and I go with the standard LAR approach which does not always yield scientific correct results, so please bear with me.
No,those thin parts are old fishing rods that I want to glue gun in there just to stiffen up those unsupported sides a little. Yep, its threaded rod just for for alignment when welding :-)
The orange part is 3 x layers of 18mm quality birch plywood glued together and bolted to the base.Considering the thickness of the wood and close spacing of the steel supports under the plywood, and big surface area of the X-axis sides, I think this will be more than strong enough to bolt my X sides to without, right? There's various good reasons why I 'd prefer NOT to weld the X sides directly to the base.
I totally agree, the base structure can be build stronger for less money, but its already build, so I guess that ship has sailed :-)
I sort of agree about the X sides that's not fully supported. I thought if the rail sits on top of 10mmalu on top of 10mm steel flat bar thats on top of the ribs spaced200mm apart it would be good enough? I'll fix that and make it stronger.
As drawn the steel parts of the gantry weighs +- 60kg if I remove the 750 x 100 x 10mm piece of flat bar which does not add much apart from weight. That gives me +-100kg including z and motors which is getting a bit on the heavy side. I can shave off weight by replacing some 10mm ribs with 6mm. I also agree, in this case the round tubes does nothing apart from cosmetics (which is also important to me) but does complicate some things a little bit. I'll get rid of them and go for something more practical. Would that be a step in the right direction or is the whole steel section and rib design just a bad idea?
I love welding but I hate cutting and grinding steel, and accurately marking and drilling big holes in steel plates is not much fun either, so the laser or hi-def plasma approach just seemed more suitable. If I may ask why are so against the laser approach apart from the additional cost?
I'm glad you did not do everything in bold red as that might have pushed me over the edge an got me to build the whole damn thing from polystirene and cold glue :cheerful:
Thanks again for helping me to get this right!
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Re: Small rigid router - Design advise needed
Quote:
Originally Posted by
Blackrat
Have you priced up laser cutting yet ?
One large dia tube is going to be much stiffer
Nope, I have not. I did get some parts laser cut about 6 or 7 years ago and at the time the price seamed very reasonable. I hope I'm not in for a nasty surprise. Until I get a design past the cnc police there's no point in costing the cutting:cheerful:
Yep, the big dia tube is much stiffer but there's just no practical way I've seen to make it work for a gantry router due to the reasons Silyavski listed above.
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Re: Small rigid router - Design advise needed
I see.
-IMO is very bad idea to lay the machine on anything else but steel. I will advice against it. I mean the orange part as you have drawn it is bad idea.
-I agree the design should please your eye. I wouldn't do it that way at all as my moto is "maximum efficiency, minimum effort" . I mean i advice against using steel tubes at all. Though as i see it the gantry could be left as it is if you insist on keeping the design, just take care the plate bellow the rails to be truly all supported, not hanging in the air.
-The sides definitely could not be as they are now
I mean, change everything, but if you insist keep the gantry :hysterical:
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Re: Small rigid router - Design advise needed
I haven't read this thread for some time now and I am surprised at the design of the router as it is now. It looks really nice.
Am I correct in that you will have pieces cut by laser as part of the build?
If so, why not build a steel torsion box from nothing but laser cut sections?
That would save a hUge amount of time, and be stiffer too.
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Re: Small rigid router - Design advise needed
Yep Sven, the idea is to have the parts laser cut. Interesting idea. I'm sure what you are suggesting would be possible and EXTREMELY stiff. Its amazing how stiff some of the light torsion box or honeycomb composite structures are like on the photo below
http://www.singcore.com/images/Metal-Strong2.jpg
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Re: Small rigid router - Design advise needed
I'm currently in contact with a guy who is building an extreme fixed gantry router. He can calculate this stuff in to extremes.
He suggested to me that a steel torsion box is nearly as stiff as a solid steel one and when designed right wil only need spot welding to keep it together, but can even be glued if you have the right technology available.
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5 Attachment(s)
Re: Small rigid router - Design advise needed
Ok, now its down to bartering. A friend needed some aluminium house numbers urgently and he had something I wanted, so I cut the numbers Wednesday night and swapped this
http://www.mycncuk.com/attachment.ph...id=13892&stc=1
for this
http://www.mycncuk.com/attachment.ph...id=13893&stc=1
Great deal, don't you think? :-)
Back to plan A of using I-beam for the gantry sides. The beam I got was a bit higher (254x148) than I hoped for but I'll make it work. I guess for me DIY CNC is more about what I have/can get/can build rather than building the ultimate design from the best choice of material. I also listened to the advice and went with a slightly more practical approach and used 76x76 square tubing, and some 10mm and 5mm plate and also bolt or weld the X sides directly on the base. Gantry weight is +- 60kg excluding Z. I know Y rails top bottom is the better approach but I'm thinking its going to much easier for me to get them parallel and on the same plane if I put it on the front. I'm hoping the laser cutting is not going to be too expensive otherwise I'll have to go for plan B with the gantry. See pics below.
Again please comment if you see any obvious issues.
http://www.mycncuk.com/attachment.ph...id=13894&stc=1
http://www.mycncuk.com/attachment.ph...id=13895&stc=1
http://www.mycncuk.com/attachment.ph...id=13896&stc=1