already have rotating nuts in mind, from the looks of it my gantry is weighing between 150-200kg so is this a deffo servo route then?
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already have rotating nuts in mind, from the looks of it my gantry is weighing between 150-200kg so is this a deffo servo route then?
200kg's! this seems excessive for a wood router a hell of a lot of weight to be moving at speed it's like 1/5 a car you'll need chuky motors.Quote:
Originally Posted by reefy86
Have you considered buying a 2nd hand router
https://www.ebay.co.uk/itm/CNC-Route...IAAOSw1cNaOuvj
haggle with them you might get it for £4.5k ;) I find if you visit people and wave cash at them you can get some leeway ;)
If you are tight on money for the build, you could buy cheaper square rails than Hiwin. Find a good factory and buy from them. it will be wise to make a plan and follow it. My machine cost me somewhere around 6-7k totally. 8x4 machine can not be made properly for 5k. you have 3k for rails, ballscrews and so, 2k for electronics and motors, 1k for metal for frame and so on. Though i lied to myself some time that i can make it for 5k.
And i had all necessary machinery and skills to design it and make it 100% by myself. And not first build, mind that.
So make a plan, follow it, be persistent, do not make any mistakes and you will do it.
this might be a stupid option for some people but i would prefer to build it rather then buy one just purely for the knowledge i will learn on the way and if something ever packs up in the future then i will know how to fix it. 200kg is alot of weight just for cutting wood but there will be a lot of rapid movements for 3d so i need the gantry to be solid. i was thinking about fixing the gantry and moving the bed but i have future plans so i will need the space for other things.
It will be impossible to move such big bed, The gantry is the way. I am sure you will manage to weld it. I learned to weld on my first machine and stick welded it. Did not have a Mig at that time. It even turned good. Think what i am telling you about the Chinese square rails, they will save you some money. In fact last time i bough they were Hiwin quality like, almost :-). But were proper steel.
will look into those boyan but it aint one of those things is it where its 50/50 if you get shit rails or hiwin like? only reason why i am going hiwin is because there is 100% guarantee i will be getting quality.
I only have 15mm Hiwin's but I have originals on the Y axis and clones on the X I can't see a difference but let's see in a year lol.
Would I buy clone again without blinking but get the right clones so the rail is compatible (Like mine) then you can swap original Hiwin's carriages onto the rail if you're carriages ever failed.
I was thinking of buying 2nd hand next time
http://www.ebay.co.uk/itm/THK-NSK-IK...19.m1438.l2649
carriages can be repacked with new bearings if needed which is essentially a recondition as long as the rail is not nicked. I have seen lots of 2nd hand rail never seen it physically damaged, rusty yes but not chipped. The carriages are what seize on old machines left outside. The rails do go rusty but much slower than normal untreated steel possibly due to years of greasing in their pasts.
whats the longest bit you guys have used without any deflection or breakage? beginning to think having a long z height is limited by the tool bit for 3d work. i can see that on some areas where i need to penetrate 300mm then either the router is going to collide or the bottom of the front plate will.
It all depends on what you are cutting, There is somebody on here making surfboards with long cutters out of a type of foam.Quote:
Originally Posted by reefy86
Also think about if you are gonna use drills as they can be longer than routerbits.
I got the tip to calculate z travel/clearance based on thickest material and longest drill I plan on using :)
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most of the 3d work will be on mdf
Any chance you can use layering in your CAM setup to cut the piece in layers with registration pins for cutting and reassembly? I know it depends on what you are making, but just in case this is for something like MDF moulds, it might do the job.
It was a thought but joining those pieces together and making it look seamless on some pieces maybe tricky.
how much room play do you leave when drilling and tapping? for example i am using 20mm linear rails on the z axis and the screw clearance is 6mm so i would need to use smaller bolts then 6mm to make room for alignment.
I made a huge error when drilling/tapping my first plate. Went with m6 as the holes were 6mm and chinese drawing said m6 holes.Quote:
Originally Posted by reefy86
Turns out that m6 boltheads couldnt fit the countersink in the rails :D
So use m5 bolts, 4.2mm drill..
That gives you 1mm adjustment.
Done correctly thats plenty ;)
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Thanks i had m5 in mind but wanted to double check :)
I used M5 as well - works fine and although you don't have a lot of adjustment range, there should be enough if you are careful. I made up a steel drill guide (a short length of steel bar with a 4.3mm hole through the middle) that had a reduced diameter one end that fitted the counterbores in the rail so it centred the drill accurately. You can then use a similar guide with a 5.1mm hole to guide the tap so that it goes in square.
M5 too here.
The first of a set of 20mm hiwin X axis rails takes a lot of time to line up to what ever straight reference.
I checked 100 times before drilling the first holes.
After squaring up the gantry to the first rail, the second rail (X) wend a lot faster using the gantry as a guide for the second rail relative distance.
I clamped down using 3 clamps before pre drilling 3 holes over 1830 mm span, ends and middle, with a 5.9mm drill, to remove epoxy and centre drilling a centre hole for 4.2 mm drill.
I have a well balanced, old :-) battery drill.
Its easy to keep vertical 90 degrees to the surface and used no other tools.
I used the 6mm hole from the rail for a guide icm with the 5.9 epoxy removal / pre centre drill and drilled 4.2 and tapped all m5 free hand with the battery drill.
Bought 2 machine taps m5 and 5 4.2 drills from toolstation (volkel) did about 100 holes in 4mm steel with 1 drill 4.2mm (ground hss) and 1 tap and still going strong.
Just use oil on drill and tap, and vacuum clean all holes before tapping.
I have had no problems with off centre holes or problems tapping the treads.
After tapping there is some wiggle room but not a lot about 0.5mm ...
After torqueing down the m5 i have had no binding trouble in the carriages.
Hope this helps.
Grtz Bert
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Thanks guys, just would like to ask a question that i can't seem to find the answer to on the forum But has anyone ran a machine for multiple years using epoxy resin without it weakening over time? also what methods do you do to get top and bottom rails lined up to exact same position?
Attachment 23546
Got my keys today for my workshop so will be cracking on soon :)
Hi reefy86,Quote:
Originally Posted by reefy86
I would like an answer to the epoxy question to :-)
For Y rail alignment?
I used 2 extruded profiles across the x rails in front of an behind the gantry.
And 2 across on top of them, parallel to the x rails under the gantry.
Now you have 2 flat references to put 2 machinist squares on. in a horizontal/ upright position on both sides of the gantry.
In the same X rail level plain.
The bottom of my gantry is half raised 12+ cm over the X rails.
I moved the rail so the carriages are just over the edge of the beam so it is close as possible to the Z axis side so the machinist square just touches them and not the gantry box section.
The rail is on the edge of useable flat of the epoxy.
Hope this helps.
Some left over extrusion 8040 goes a long way for alignment purposes.
I did check them for resonable straightness before using them this way.
You need square and flat references all through the build, i did under estimate this.
If not for epoxy this would never have worked out for me.
Grtz Bert
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What do you think of my idea which probably some of you may think its a waste of money on the extra epoxy resin.
There will be 2 gantry sections so the z axis is boxed in the middle.
this is just a quick rough up, the red pieces are the epoxy resin fully cured
1. weld the steel box sections together
2. lay the sections down on a level surface and pour epoxy resin
3. after 10 days or however long it takes to cure flip the sections back to normal position.
4. attach gantry side plates and adjust and bolt to as square as you can get it.
5. again pour epoxy resin to level both sections on the same plane
6. attach the linear rail on the front of the sections and then use a magnetic gauge indicator and use the top to line up the rails.
https://youtu.be/um99ZZCk4LA
Would like some opinions on the above please :) in the meantime i am purchasing necessary tools to get the job started but would like your input if possible.
1. how accurate of 1800mm straight edges and if someone can recommend one if the cheap ones are no good.
2. is bigger the better for the engineer squares? seen some 300mm ones but are nearly £100 each
3. anything else you recommend i should buy to make things easier on the way?
I know you guys are probably sick of hearing from me now lol but things will actually be getting done once i have ordered the necessary tools.
I dont quite get it.. will one set of rails be on top and 2 sets in between? :DQuote:
Originally Posted by reefy86
For question 1 you should read boyans build threads. Somewhere in there he states DIN numbers for the necessary straight edge and where to find them. If Im not misstaken he also wrote about the squares..
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no just 2 sets in between and the epoxy on the top is just a reference for the gauge indicator, one some videos people sit a magnetic block onto to linear bearing blocks and the have the gauge indicator touch against the aluminium extrusion all the way down the rail until its square but aluminium extrusion is not perfectly straight but with the epoxy resin being very flat and straight then i thought doing it this way may work.
Now I get it, smart! ;)Quote:
Originally Posted by reefy86
I have been using a dti alot lately.. was so hung up on aligning my rails (went fine) that I more or less forgot/neglected the ballscrews, bearings and ballnut..
If you get a dti make sure it has a good holder (if its called that) with a strong magnetic base.
Mine is utter crap and its frustrating when you hand turn the ballscrew with everything mouted from one end almost to the next and the dial tip just moves off the reference. Not worth the 5-20 you save on a cheap holder :)
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I have no idea what its called i just call it a gauge indicator lol.
DTI Dial Test Indicator
that's me I use a 7" bit and have around 9" of z travel but you wont cut much more than foam with itQuote:
Originally Posted by Clive S
Haha I ment the base or mount or whatever you call it.. make sure you get a good one!Quote:
Originally Posted by reefy86
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Cheers mate, still need to brace the bed frame a little more at the bottom and brace the side gantry plates but would like some feedback if anyone thinks i will run into any problems. will be extending the bed by another meter at the bottom for a 4th axis, z height is 200mm but can also do up to 400mm by making the 4th axis centre in line with the bed so with the z axis boxed in do you think this is strong enough for what i wanted it for?
Attachment 23567Attachment 23568Attachment 23569
I have to say this, are you serious about building this cad model !! for a first build !!. because this style of gantry is going to be very difficult unless you have a lot of experience and good tooling to make it. I would take a step back and think what you are taking on.
Please don't be offended.
Im impressed, so I have to cheer you on :D
I know myself so I know I could never do this without access to a finished cnc router.
Take it slow, be super careful and think about where you need adjustment capability.
If you pull this off you can be mighty proud
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No worries Clive if i get offended by someone being honest that easy then there is no way i can succeed lol. it is a big job but this is not something i am expecting to put together easy so i am preparing my self as i go along, i Don't have the necessary equipment like alot of you guys do so this is where i am putting alot of money into having the aluminium plates machined for me from nice guys who have the equipment to do it which i have had a few nice people offer their services :). i have not seen anyone do this but i don't see why it wont work but using the epoxy resin method that i shown will help have the 4 rails all lined up as long as i make room for adjustments on the gantry side plates and bearing plates then it should help getting the gantry square easier. Also i know there is the sandwich problem when having the z axis like i have but the way i have done it is so the 2 front rails and the front z axis support plate doesn't have to be connected to the rest of the z axis yet as long as its still on the same level as the 2 back rails hence the epoxy idea. now as long as i make room for adjustments and as long as i am careful and everything is aligned and straight as i can get it i will be relying on the aluminium plate edges to be machined flat so i can use those edges to help square up the z rails. Pretty much its going to cost me a lot of money just for these extra ideas where as you guys would get it done next to nothing because you have the skills and the equipment to do it :)Quote:
Originally Posted by Clive S
Thanks mate appreciate itQuote:
Originally Posted by Nr1madman
Ok, well you are braver than me. Have a read through this thread I think it is the only one with a Z axis like you are proposing http://www.mycncuk.com/threads/9369-...ain-MK4/page22
The tolerances have to be spot on when using Hi win rails as they will bind up.
Good luck with the build I am looking forward to it.:thumsup:
thanks mate will keep everyone up to date, just need to finalise frame design so i can order the steel and crack on with it.Quote:
Originally Posted by Clive S
Hmm how about jonathans build with the red frame? Didnt that one have similar solutions?
:D
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I think this could be a very serious challenge to put all together with the needed precision. This designs is not stronger than my design. Which is simpler. More rails and more head scratching.
Hi Boyan, I was trying to keep the z axis very strong using the box design so would you say a single beam is more then capable? or is there something else that you think is over complicated.Quote:
Originally Posted by Boyan Silyavski
cheers
I think you are from those type of people that will not listen to reason as you all ready have decided your way and you like challenges. This impression i have from the thread and our PM. So i don't want to discourage you, as if i say what i think and you listen to me, will have to start from scratch :hysterical:Quote:
Originally Posted by reefy86
Whatever way to do it will be possible if you are persistent and have enough time. So no worries, if this is what you feel is the way. For me this is a design for an experienced machinist who has a mill at home. What more to say.