This story is about Steel Gantry Machine with work-area 1500x750x200 for aluminium and wood.
First I was going for a fixed gantry machine but bigger work-area changed my mind. As long as I have to purchase expensive components the price difference for longer components is not so dramatic - but it gives nice advantage.
Main frame welded steel 80x80x4mm.
Steel gantry consist of 2 pcs 100x100x3mm tubes welded together and some 8mm steel plates.
Z assembly is mostly 25mm aluminium with 2,2kw watercooled spindle.
Ballscrews X,Y=1610; Z=1605.
HIWIN 20mm rails all axes. Epoxy leveled.
Please feel free to comment my design. In case of positive feedback then next step would be to order rails and ballscrews. Measure them and then finalize design and start the build.
I have couple of questions for more experienced guys:
- Can I use L (0,375" = 9,525mm) pitch pulleys with a 12,7mm wide belt from steppermotor to ballscrew? I can get those pulley for free. Together with 240L belt. But this belt is too long and pulley centre hole is 10mm, whish I cant use on Nema 23 anyway. So I have to buy half the pulleys and belts. May as well buy proper with belts and pulleys all around?
- What ballscrew machining are you using when belt pulley will be attached?
- Hole gantry with Z and everything will be close to 80 kg. Can I put my money on 2x Nema 23 3,1Nm together with a decent 70Vdc PSU?
- What HIWIN blocks do most of you prefer: HGH or HGW? Sure it depends from design but I think I will go with HGH20CA from BST Automation.
Tanks for reading!
The bed looks quite low on this, you may find the z axis is unduly extended if cutting mainly sheet material. That said I don't know what you plan to cut? Looks like a nice strong frame, you will want some leaving feet on it particularly if going for 6 legs...
The Following User Says Thank You to JoeHarris For This Useful Post:
I would limit Z axis movement with proximity switches to about 100mm + detachable smaller workarea bed when aluminium cutting. This will keep Z in sweet-spot while cutting but also adds weight. I choose unnecessary weight over adjustable bed? But now when I think about it... I will get both actually! Will have to think this over.
Also I have made some updates to the model.
Do you think this long 1610 ballscrew will start whipping on X-axis?
Hi, good luck with your build!
Use well the spindle itself for strengthening the Z plate.
However your Z design slightly but critically differs from mine,may be its its weaker, please show better and closer pictures so we could see it in detail/, you could again read when you have time my first build/link in signature/ how exactly i made the Z.
At my second build i was again at the point of making the same mistake as at the first one. Same as what you are doing here. Trying to save on frame bed and machine weight. Now checking prices of T slot track, T slot solid aluminum, T slot aluminum profile, plain aluminum sheet and plastic sheet, i have it quite clear: The bed must be as strong as possible, crossing profiles as near as possible even bed made of welded profiles as the gantry is made, if you will do mainly aluminum.
Why that? Cause all else for serious fixing is darn expensive. Now i am hitting my head these days why i did not weld solid profile 1/2 of the bed for the 2600x1300 i am building for my self now.
So my recommendation here is to make the near to you half of the bed very strong as possible. So later you will not need to pay ridiculous amount of money for aluminum sheets and so.
What i am saying is you weld a strong structure for bed with the chosen profile. Then go to somebody who has shop, like a welder or machine shop. Ask them for their scrap and rests of different profiles. And that cheap stuff you use to weld in between to make it solid. It could be thin walled.
Last edited by Boyan Silyavski; 08-03-2015 at 07:44 AM.
The Following User Says Thank You to Boyan Silyavski For This Useful Post:
I will go with HTD belts then.
Ballscrew standard machining leaves 15mm space for the pulley. Standard pulley is about 26mm. How do you solve this?
I think Silyavskis steel Z axis is coolest one I have seen :) I have studied that design but dont feel certain that I can pull it off. As I have good access to 20-25mm aluminium flatbars I go with the "usual" aluminium Z axis design.
Btw what is the weight of you steel Z axis, Silyavski?
I will beef up the frame and will rethink the bed fixing system.
I need to order rails and screws before EURO is totally useless :(
The Following User Says Thank You to JAZZCNC For This Useful Post:
I agree Dean. I was deep into reading about HF plasma grounding and just glanced at it and thought 1500 total length of screw -300mm in gantry legs gives 1200, minus more when he betters the design, so he could go away with that, cause anyways most people don't go faster than 10m/min in real life. And it was 1500mm travel , not screw length. I hope he did not order the screws. Anyways i will buy them from him if that mistake happened. its never a bad thing to have some extra ball screws.
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