[andtfoot]

Hey all, long time lurker here.

After years of looking, thinking, pondering, money-saving, etc... I have finally started.
(Money is a bit tight at the moment, so it may take a while to finish though. Isn't that always the way?)

The general plan is a moving gantry system using aluminium extrusion as the frame. I'm hoping to mainly cut wood with a guitar being a definite goal, but I'm also hoping to do some light aluminium stuff at some point. So far I have bought the following:

Ballscrews - from 'solar.jean' on eBay
1 x RM1605-350 ballscrew + nut
1 x RM1605-550 ballscrew + nut
1 x RM1605-850 ballscrew + nut

Supported rails - from 'solar.jean' on eBay
2 x SBR16-300 rails with 4 x SBR16UU bearings
2 x SBR16-500 rails with 4 x SBR16UU bearings
2 x SBR20-800 rails with 4 x SBR20UU bearings

Spindle - from 'solar.jean' on eBay
1.5KW air-cooled spindle + Huanyang VFD + Mount

Stepper motors + driver - from Homann Designs
Gecko G540 kit with 3 x 387oz/in. nema23 motors

Motor couplers - from 'wholesale-eshop' on eBay
3 x 6.35x10mm helical couplers


For the framing, I was going to go with AME System 40 series. I'm doing a rough design now so I can order enough.


Anyway, here is the general gist of the design I'm planning out. It's all 80x40mm extrusion so far. I'm going to be adding gussets where possible to any 90 degree angles.
I'm currently trying to extend the Y axis slightly to fit a guitar body. I think I under-bought on the rails and ballscrew, but the package for the 3 axes was a great deal.



I haven't decided on software yet, but I'm at least thinking of Mach3 for the control.

There is going to be a fair margin of winging it on this build, I think... I'm open to any comments or suggestions.

[andtfoot]

Links to the suppliers (I couldn't add before, due to first post):

solar.jean on eBay

wholesale-eshop on eBay

Homann Designs

AME System 40 series

[harryn]

Extrusions are a great aproach to building a machine, but it doesn't come at a low cost. I really wanted to use extrusions too, but combining the price of the extrusions, and the fasteners (nearly as much as the extrusion price) and it is a budget "challene".

I know it sounds harder, but seriously consider to make your frame from steel rectangular tube and bolt or epoxy it together. The materials cost will be 5 x lower.

[andtfoot]

Extrusions are a great aproach to building a machine, but it doesn't come at a low cost. I really wanted to use extrusions too, but combining the price of the extrusions, and the fasteners (nearly as much as the extrusion price) and it is a budget "challene".

I know it sounds harder, but seriously consider to make your frame from steel rectangular tube and bolt or epoxy it together. The materials cost will be 5 x lower.

I have briefly looked at both options, but I keep on getting the feeling that the extrusion would be easier to tinker with and still get a decent result. I had figured I would pay a premium for this flexibilty and factored it in, so I'm still leaning towards it.
I may toy with the steel tube idea some more though. Thanks for the suggestion.

[andtfoot]

While I financially recover after an impulse buy from an A/V supplier's sale at work (got some good deals though ) I've done some more conceptualising...



I've added the motors, flattened the Z-axis a bit, expanded the size of the table to use the rails better, and beefed up some sections. I've also tried to allow plenty of room to beef it up more if required.

There are still a few details missing that I need to think about though such as routing wires, the table surface and dust management. Still toying around with software ideas as well. Installing a demo of DeskProto now...

[JerryBurks]

Looks good!

I think the single biggest improvement would be going dual x-screws. This is a good-size machine and the forces on the linear x-bearings will be significant when the y-axis is on its limits. The linear ball bearings are pretty good but the racking leverage near the mid/neutral point is infinite, especially with the short distance between the bearing blocks. If you have dual screws you can also drop the connecting bar under the table saving complexity and recovering some cost of the additional drive.

You may also consider turning the z-rails 90 degrees to be opposite direction. The way you have it now the z-bearings are all in the "weak" direction (i.e. pulling the bearing from the rail) when moving to "-x"

[andtfoot]

Looks good!

I think the single biggest improvement would be going dual x-screws. This is a good-size machine and the forces on the linear x-bearings will be significant when the y-axis is on its limits. The linear ball bearings are pretty good but the racking leverage near the mid/neutral point is infinite, especially with the short distance between the bearing blocks. If you have dual screws you can also drop the connecting bar under the table saving complexity and recovering some cost of the additional drive.

That's one of the main reasons I'm pretty set on using the extrusions. It would not be a big task to add the extra motor if needed. In the meantime, it's only $30 of material vs. extra ballscrew, bearing blocks, motor, etc.
I'll do some research, but do you know off-hand how I would connect the extra motor?

You may also consider turning the z-rails 90 degrees to be opposite direction. The way you have it now the z-bearings are all in the "weak" direction (i.e. pulling the bearing from the rail) when moving to "-x"

I'm guessing you mean something like this:

It pushes the spindle out a little bit, but as you said, spreads the load on the bearings better.

[andtfoot]

There hasn't really been much movement on the build at the moment. I've mainly been stocking up on other stuff I will need:





I've picked up a few bits of steel so far for attaching the linear bearings to, but I'll probably hold off on the rest until I get the aluminium.

[dodger889]

Here is a hint for those that are thinking of using a setup like this. Look at where your work point( tool area) is to where your slide or bearings area is. You will want to keep the work area in between the bearings. This will keep your z axis from binding the x axis.

[andtfoot]

Here is a hint for those that are thinking of using a setup like this. Look at where your work point( tool area) is to where your slide or bearings area is. You will want to keep the work area in between the bearings. This will keep your z axis from binding the x axis.

Rightio. I generally thought the idea was to keep the mass over the center of the bearings, not the cutting tool, so I thought I was just scraping in.

Either way, I've thought of an idea where I will use longer rails for the bearings to sit on, and drill holes at regular intervals to allow repositioning of the bearings. That way if I need the extra bit of travel, but not rigidity (wooden guitar neck, for example) I can temporarily tuck the bearings in a bit closer.

Something like this:


This is the steel I picked up for the purpose. I got a decent length at a good price, so I should have enough to play with.


As you can probably see, I haven't decided how I want to drive the Y-axis yet. I'll probably run something on the back side of the rail that joins the top and bottom bearings attached to the Z-axis, and drive that. It's probably not ideal as it away from the work point, but it keeps it away from the dust I suppose.

[dodger889]

Your torque from the z axis is what will be cause the binding of the y axis rails and bearings. Now with that thought in mind you will want to spread that torque out over the largest area you can afford. This will help control that twist and keep the play out of the system. Now if you are wanting to go beyond the end of the table. Make the y rail to extend out farther.

[andtfoot]

I've pretty much decided I'll go with the latest design. If I run into any issues, I'll sort them out then. That's my whole reasoning for the bolt together structure.

That said, I may have to weld some bits. I picked up some 90x8mm steel flat bar today, with the intention of using it for all of the remaining brackets, motor mounts, etc:

The large piece is 200x8mm stuff to bolt the spindle mount to.
Depending on how straight I can cut, I was thinking of either bolting bits together at right-angles, or welding it.
Welding will be easier to fudge together poorly cut stuff, and if I leave a decent fillet on the inside edge will be stronger by itself too. The downside is it's definitely harder to modify.

Anyone got some good tips on cutting steel straight without spending a fortune?

[TheWP]

Anything come of this project?

[andtfoot]

Sorry for the lack of update...

Anything come of this project?

Nah, I ended up grabbing a Carving-CNC body kit, and adding the stepper motors, Gecko driver, and spindle+VFD I had already bought.
CNC Engraving router 6040Z-s80 mainbody - carving-cnc.com

It was a bit finicky to get lined up to a decent level (it could be better still) but good enough for what I've been mucking around with so far, which is some wood stuff, plaque engraving and circuit boards. I'm mainly limited by my own ability with CAD/CAM and workpiece holding/prep at this point.

First cut:
CNC - First cut - YouTube

V-carve inlay on a banjo I built:


Engraving on circuit board material:

[TheWP]

Thanks for the quick reply.

So was it the cost, concerns about accuracy, level of difficulty?

(Good stuff btw)

[Dean Elliott]

In an effort to consolidate all of the 6040 and 6040z threads please post here: http://www.cnczone.com/forums/open-s...ml#post1790768