[kolias]

This is my new cnc constructed with 1/2" thick 6061-T6511 Aluminum Flat Bar / Plate; the top (cutting area) as well as the two Gantry pcs and all the X & Z axes pcs will be with Aluminum tooling MIC6 plate. I have chosen the Zinc coated socket head cap screws just for the looks. In comparison, the same screws in black oxide finish are half the cost.

The two Gantry pcs are temporary for now and I will remake them when the cnc is working is an “S” shape to provide better weight distribution on the X axis.

The cutting area will by Y=36”, X=26”, Z=12”. The bottom white table has caster to move the machine when needed plus levelling legs to level the machine in the new location. The linear rails and ballscrews are from China (Chai). I have chosen the ER16 Taig Spindle along with the Sherline Variable Speed motor and their two step pulleys. This combination will give me a good choice of speed.

The Gecko G540 4 Axis drive will drive the four motors which are 276oz.in, 2.8A and they have these covers at the end which makes for a neat installation. All electrical items and the spindle were purchased from Soigeneris.com who provided me with an excellent service.

As the build continuous, I will be adding more pics and info

[DonFrambach]

...
The cutting area will by Y=36”, X=26”, Z=12”.
...

That's a lot of "Z" axis travel. What are you going to cut that needs so much?

Penalty for lots of Z travel is rigidity.

[kolias]

I agree Don that the Z should not have a large travel

Before my build, I made a model out of plywood and these are the approx. dimensions from the model. As my build progresses, I may have to adjust the travels to maintain rigidity

[ger21]

If you decide to change the gantry sides, you might want to consider spreading your Y axis bearings apart by 3-4". You'll lose that much travel, but should gain a lot of rigidity.

[kolias]

The reason I went with 4 bearings per side on the Y axis is to provide rigidity and spreading the bearings apart the better. I’m thinking about this idea and planning to do some test when the Z axis is completed to find out the benefit of less Y travel vs rigidity

[aarggh]

Teriffic looking machine Nicolas! Did you a follow a formula for working out the placement of the rails/screw in relation to the height of the gantry, or just eyeball it and do what felt or looked good?

I'm looking at a two rail design myself for a build i'm planning when my garage is (finally) finished, but there doesn't seem too much online for optimal placement for dual linear rails.

cheers,
Ian

[kolias]

This is my 3rd hobby CNC Ian and I found the following link to be very useful

Homemade CNC Router The Builder's Guide (FREE!)

I also made a model out of plywood to see how the parts react and found the model to be a great help. Ultimately the best would have been to draw the cnc in ACAD or something similar but that requires 3D knowledge which I don’t have a lot.

It is true that I have not seen any two rails design either and my idea was that since the moving Gantry will be heavy it will be better to provide two rails on Y & A for stability

Good luck with your machine

[pending]

I would strongly suggest 1" thick aluminum at the very least and linear guide rails. Mine didn't perform as rigidly as I had hoped(I used .5" aluminum). Mainly the gantry you will notice is has some give and the supported rails also supply some give even when you attempt to give them some pretension. Looks great though I'm sure upgrades won't be difficult since you got the basic design down. Also wanted to add you will basically have to have linear guide rails on the z axis as you will find lots of slop if you don't.

[kolias]

Pending not a downer at all, comments are always welcome

I don’t think 1” thick aluminum will be more rigid because increasing the mass creates other problems. If I see that my cnc is not as rigid as I was planning, then I will have to modify my design. But this is only my opinion and each one of us has their own

[kolias]

Here are some pics of the finished Z-Axis

[DonFrambach]

Here are some pics of the finished Z-Axis

Looks very nice. How are you going to mount your spindle to the Z-axis?

[kolias]

Thank you Don, the spindle will be mounted on a 3/8” thick aluminum plate and this plate will be mounted on top of the Z axis plate you see on the pics.

I have ordered the Taig spindle but there is a delay on shipping and I should get it around early August. I have a concern with the weight of the Z axis especially with the straight members I now have on the gantry (I plan to cut new “S” shape gantry pieces when I get the cnc going and this will distribute the weight more evenly); what you see on the pic weights 12 Lbs + another 8 Lbs for the Taig and I still have to add the motor which I don’t know yet how much but I suspect it will be around 10 – 15 Lbs.

I think you had a Taig on your machine Don. What was your Z total weight including the motor?

[DonFrambach]

I think you had a Taig on your machine Don. What was your Z total weight including the motor?

Sorry, don't have the total Z-axis weight. I did weigh the Taig spindle, Taig mount, Taig motor, and BD tools adapter for quick belt changes (which I highly recommend - though he has raised his prices from high to very pricey). Weight is 15.8 lbs.

Here's a photo to show you what I weighed:

[kolias]

Your Taig assembly looks very neat, thanks for the pic and weight

Yes I like the BDTools adapter but you are right, too pricey. When I get my cnc going I may make something similar

[DonFrambach]

When I get my cnc going I may make something similar

I shouldn't be hard to duplicate.

[kolias]

Here are some new pics of my build. Due to my concern with the weight of the X axis, I had to re work the gantry and installed 2 new pcs 18” long vs 14” of the old ones. The extra height allows me now to support the X axis on 9-1/2” c/c vs 4-1/2” with the old pieces and still have 5-3/4” clearance to the table.

In addition and as you can see in one pic, the center line of the X axis can now reach the table edge and this means the width of my cuts could be 24-1/4”. I could increase this width by 1” if I relocate the bottom slides closer.

The Taig spindle should be here any day now and then I will complete the mechanical build and start the electrical (more fun then)

[aarggh]

The builds looking fantastic Nicolas! Therre's something about a solid aluminium cnc that really looks appealing.

I do suspect though that you'll get some sideways flex and/or twisting on the gantry, especially under load, are you bracing it any further? A brace along the top that would bolt to both sides as well as the top plate would greatly increase the rigidity. It's important when adding bracing for it to bolt to two planes (contacting a horizontal and vertical edge of two or more pieces), when it's just one it does tend to allow a degree of movement. This will also help towards stopping any "racking" at speeds.

cheers,
Ian

[kolias]

You are right Ian, I was planning to do this build with 8020 extrusions but when I saw a solid aluminum cnc I said that’s what I will do. Much more work to cut the pcs and do all the drilling / tapping but on the other hand much less expensive too

Yes I plan to brace it later on; now I just install the parts and when the mechanical is done I will brace the gantry. Thanks for the help

[kolias]

The Taig spindle is now installed and looks great. I decided not to use the old VS motor I have and get the Sherline VS motor which means I will have to wait for another 2 weeks for the delivery.

I may counterbore the slots which hold the Z axis with 4 bolts if I see that they interfere or I may cut the plate and eliminate the slots although I feel that they provide more flexibility.

The X axis motor is now installed

[DonFrambach]

Very nice. Is that a Sherline pulley on the Taig spindle?