John's Alu Profile build

[Evengravy]

Hi John
Regarding vertical mounting you will have to build yourself a substantial base, if you make another post asking for ideas for designing a vertical assembly machine Dean(JAZZCNC) might give you some advice regarding this, he has a video of one of his larger builds but i couldn't find it.
Regards
Mike

Okay, thanks a lot, I'll have a think about some options.

[JAZZCNC]

Hi John
Regarding vertical mounting you will have to build yourself a substantial base, if you make another post asking for ideas for designing a vertical assembly machine Dean(JAZZCNC) might give you some advice regarding this, he has a video of one of his larger builds but i couldn't find it.
Regards
Mike

That would probably be this 8x4 then. 10 x 5 with a Vacuum bed will be coming soon if I ever get out of this bloody house again.!!.

The vertical machine works amazingly for large machines with no downsides other than cannot use it as a bench. The advantages are many and I wouldn't go back to a horizontal machine if larger than 4x4. That said I'd still have a vertical machine under 4x4 for some of the hidden benefits like longer tool life and better chip management but below 4x4 the space-saving isn't so great.

Regards the filling of tubes then I've tried sand and while it does help a little it's not a massive difference. Don't fill tubes with concrete because it can shrink, it also doesn't mix well with aluminum. Expanding Foam and Silicone etc don't do diddly squat so don't waste your time money.

The best thing I found is to use a thicker wall tube in the first place and brace it well. Regards the aluminum profile then if you use HD version then you shouldn't have any issues with vibrations and I don't think to fill the voids with Epoxy granite will dampen to any great degree but it will certainly affect performance because of the extra weight.

[Evengravy]

That would probably be this 8x4 then. 10 x 5 with a Vacuum bed will be coming soon if I ever get out of this bloody house again.!!.

The vertical machine works amazingly for large machines with no downsides other than cannot use it as a bench. The advantages are many and I wouldn't go back to a horizontal machine if larger than 4x4. That said I'd still have a vertical machine under 4x4 for some of the hidden benefits like longer tool life and better chip management but below 4x4 the space-saving isn't so great.

Regards the filling of tubes then I've tried sand and while it does help a little it's not a massive difference. Don't fill tubes with concrete because it can shrink, it also doesn't mix well with aluminum. Expanding Foam and Silicone etc don't do diddly squat so don't waste your time money.

The best thing I found is to use a thicker wall tube in the first place and brace it well. Regards the aluminum profile then if you use HD version then you shouldn't have any issues with vibrations and I don't think to fill the voids with Epoxy granite will dampen to any great degree but it will certainly affect performance because of the extra weight.

That's awesome! This has given me some ideas for sure... Design wise it's not a million miles away from mine, I really wish I could weld. Maybe I can think of something I could make work using aluminium profile.

Ten four on the cement filling. I think I'll go with sand on the Y rails that don't need to move just for the added benefit, and try some test pieces for composites on the X gantry, to see if it's worth the hassle. I can't recall if it was HD rails, it was this type of profile from Dold Mechatronic: https://www.dold-mechatronik.de/Alum...-type-groove-8 maybe there is heavier type out there and that was my mistake.

[JAZZCNC]

That's awesome! This has given me some ideas for sure... Design wise it's not a million miles away from mine, I really wish I could weld. Maybe I can think of something I could make work using aluminium profile.

Welding isn't that hard, esp if you can get your hands on a Mig welder. You can even hire them from some a decent hire shops.
The welds don't need to be industrial strength. Steel is very forgiving so it allows you a few attempts if get it wrong and along with a grinder you can hide all your screw ups away.

I can't recall if it was HD rails, it was this type of profile from Dold Mechatronic: https://www.dold-mechatronik.de/Alum...-type-groove-8 maybe there is heavier type out there and that was my mistake.

That is the ITEM "L" section the "L" stands for light. It's exactly what you see on that vertical machine but I'm using the heavier version which doesn't end with "L".
However, I've used the "L" on many machines and it works perfectly fine so I wouldn't be too worried.

[Kitwn]

John,
I haven't tried this but have wondered if polystyrene concrete could be used to damp the gantry without it getting too heavy. I found an article once (don't have it to hand I'm sorry) that described using up to 60% by volume of polystyrene beads (you can buy them for making bean-bag furniture) to make concrete for light-weight structures. It's still quite strong at that percentage and I think the density came out at a little over 1Kg/litre.

[Evengravy]

John,
I haven't tried this but have wondered if polystyrene concrete could be used to damp the gantry without it getting too heavy. I found an article once (don't have it to hand I'm sorry) that described using up to 60% by volume of polystyrene beads (you can buy them for making bean-bag furniture) to make concrete for light-weight structures. It's still quite strong at that percentage and I think the density came out at a little over 1Kg/litre.

Hey. Thanks! That's quite interesting. I was thinking of something similar with perlite and concrete or epoxy. I was told that concrete may react with aluminium though somewhere but I can't recall where exactly. Does a anyone have any insight on that? On this note I was looking at some local companies that sell recycled tyres, chipped up for playgrounds. I was thinking that could make a good aggregate for a damping composite maybe, with either epoxy or liquid platinum cure silicone to bind the chunks together in a similar way to making epoxy/granite.

It sound like some tests might be in order, luckily I'm an acoustics specialist with oscilloscope etc here so could at least test a few solutions on a small scale.

[Kitwn]

It sound like some tests might be in order, luckily I'm an acoustics specialist with oscilloscope etc here so could at least test a few solutions on a small scale.

You're the man then! I like the idea of bendy concrete made with old tyres

[Evengravy]

You're the man then! I like the idea of bendy concrete made with old tyres

Thanks. Sure, I'll do some more in depth reading and maybe some tests soon, the complication at the moment is getting out of the F'ing house to get materials but gives me chance to do some research if nothing else.

I came across a guy on another CNC forum that recommended bitchumen (tar) plus sand, that could potentially be a cheap and available solution, if it isn't too heavy that is. Maybe roofing tar plus rubber chips. Certainly it's common to use roofing bitchumen sheets (old school roofing felt) in acoustic dampening solutions in a studio environment, I see no reason why it wouldn't transfer here, in theory.

Silicone would likely be expensive but should be quite efficient, maybe recycled rubber plus a binder might help. It's always going to be a tradeoff of weight vs dampening factor for a gantry though.

It's simple enough to test smaller pieces in practice though; with a contact mic/measurement mic and some shorter pieces of profile and an oscilloscope, I have some 80x80mm profile I could donate to the cause so I could side by side a few possible solutions as an experiment. Could be useful to see what approaches might work down the line.

At the moment, I'm just awaiting the new ballscrews to arrive so I can get rid of these cheaper ones.

Thanks for chipping in guys, appreciated.

[Evengravy]

So,

New ballscrews have arrived, TBI motion ground 2005 with double nuts. These ballscrews have BK15 mounts at both ends rather than a floating end and each BK15 holder, four in total, has a pair of Japanese 7002 angular contact bearings. These parts were bought lightly used from the same seller that I bought a lot of the other parts from in South Korea, but are clearly much better than the Chinese ones that I'm going to pull off the Y axis. One of these screws will be on each side of the Y axis as before so it should improve the smoothness of motion and the extra thickness of the screw (going from 16mm to 20mm) should enable me to increase the speed of the rapid movements a little without encountering whipping.



The only downside of the change so far is that I've lost a bit of travel on the Y axis, down from just over 1100mm to just over 1000mm. I'd rather have the piece of mind of these motion parts than the extra cutting envelope so I'm okay with it.

As a result I've needed to redesign a few parts though. As per Jazz suggestion I've added a new bracing for the gantry which will tie in to the Y axis linear bearing plates. This part only braces towards the back side of the gantry, as the new ball-screw connection will be made to the front side via a plate as shown below. I might figure out something for the front too at a later date.



I've designed some new shoes for the ballscrews to fix to to mate them with the Y axis profiles.



I've also rethought the design for connecting the ballscrew to the Gantry. I was never too happy with the previous welded solution, they were a mess.



Lastly, since I've moved up to a larger screw my motor mounts have to change too. These attach to the end of the Y profile on each side and carry the Y motors.



Since I can't buy materials at the minute I've decided to try to get all of these laser cut in the UK and shipped over. The company are running but with minimal staff so it might take a while to organise.

Gantry to ballscrew mating part will be made of 15mm mild steel laser cut and I'll paint that later. The rest will be laser cut from 10mm stainless steel. That's the plan at the moment, it's hard to get companies to do much at the moment so we'll have to see.

[JAZZCNC]

Don't understand why you are making the Y ball screw plate and the brace plate separate.? This could be made as one piece and will be stiffer and easier to fit.!