[Zephrant]

BM- Did you order the aluminum pre-cut with the end jointing hardware, or did you do that yourself?

For getting true on the Z axis, can you shim between the Z sled and the bearings to help true it up in the X-Z plane, and adjust the router bracket for the Y-Z plane if needed?

Edit- Nevermind, I re-read and found your pocketing picture earlier.

But while I'm here:

Did you draw it up in full 3D, or just 2D?

Did you get "tooling plate" for the sides, or just standard plate? 6061-T6?

Zeph

[balsaman]

So far it's pretty square, but I can only measure using a square. The machine itself will be out a bit here and there but I hope some stuff I can square up by loosening, adjusting, and retightening. Other area's may need shimming. Once it's built, I will use a dial indicator to get it as close as I can, and cut a couple squares and check that the right angles are right... I am willing to accept it as good as it comes out. I mostly cut airplane parts, so 10 thousands here and there won't matter. Still, I hope to get it better than that. We will see.

I used 6061-T6 aluminum. I drew it up in 2D.

[anoel]

How rigid does it feel right now. How's the motor mount going to be done for the Z? From the picture it doesn't look like a lot of clearance for a leadscrew (but then again picures have a tendancy to compress space. Are you going to use gear reduction on the servos?

[balsaman]

There is about 1.25" in there for the lead screw/nut. I am just cutting that stuff now on my other cnc. It feels nice and rigid, but we will see when we make heavy cuts/crash . I am planning direct drive for the servo's onto 3/4-6 acme lead screws.

Eric

[anoel]

How about your cutting table are you going to go with a T-Slotted aluminum table or a wooden sacraficial table?

(I ask these questions because I see a servo driven Aluminum macine in my not so distant future...)

[balsaman]

MDF with holes drilled every inch with threaded inserts in the holes, like my last one.

Here are my end/thrust bearing in thier delrin holders. The delrin in pocketed so the open end goes against the aluminum. The other end has a shoulder to keep the bearing in there. A shoulder on the leadscrew goes aganst the inner race, and a nut on the other side.

Also see a loose bearing and one of the tapped delrin nuts.

Eric

[balsaman]

the other side of the bearing holder.

[cbcnc]

Eric,

Looks good!
That is the way I have done my bearings. I have used a aluminum holder though. The holes that attach the holders are oversize so there is some play for adjustment. Also, if they are on the backside of the frame and the hole that the leadscrew goes through is smaller than the bearing, you don't need the lip.

Chris

[balsaman]

You still need the lip to keep the bearing from pushing out. The aluminum holds it on one side, with the hole being smaller than the bearing OD, and the lip holds the other side.

Once the machine is running, If I feel the delrin won't stand up, I will make some aluminum ones.

Eric

[cbcnc]

You're right about the lip. On my x axis I have supported the leadscrew on both ends so the locknuts and washers hold the bearings in. My other two axes will have one bearing each and the lip.

Chris

[anoel]

Here's a pic of the bearing block that I used on the Y axis of my big machine. Is' just made from 1/2" PVC and Clamps around the bearing. The Skate bearing fit nice and tight and after clamping, doesn't slip .

[balsaman]

Ok so I got a little paranoid about the plastic nuts for this machine, so I made some new ones out of Inconel. It's tough as nails, I just hope not too tough that it wears my leadscrew. The 3/4" x 6 acme screw I am getting is only $15.00 per 6' length so no biggie.

[balsaman]

Cut the pocket and drilled holes in my side plate for the y axis motor. I found a severe feed rate issue with arcs in turbocnc so after I broke a 1/8" bit I went with a square pocket. It seems the feedrate is ignored while cutting arcs so the feedrate went a wee (double at least) over the F3 I specified. I never noticed this before as I usually am impatient and my feed rates are way up there when cutting wood anyways. I am waiting to hear from the turbocnc guru's if it's just me or not...

anyways here is the pocket.

Let me know if I am boring you all.

[anoel]

A little lube should keep the wear down. (a little telfon spray now and then, perhaps)

What is Inconel? Looks like a bronze derivitive from the photo.
How hard was it to tap? I know that tapping the 1/2" 10tpi holes in UHMW was pretty tough. I cringe to think what it'd be like in metal.

[balsaman]

I am not tool maker but yes it's some sort of bronze material. It taps ok, the shavings come out in little chips so that's nice.

Here is the motor mounted for now.

[Zephrant]

Looks great- Keep the info coming.

Zeph

[balsaman]

Sorry guys, that material for the nuts is not Inconel (which is like stainless steel) but Amco, which is a sort of bronze material. I got that mixed up in the above posts.

Eric

[anoel]

So when do you expect to be spinning motors? Were you able to decide upon a router motor?

[balsaman]

I need to buy the gecko's yet, and I am waiting for the lead screws...I little while yet.

Eric

[keithorr]

Originally posted by balsaman
Sorry guys, that material for the nuts is not Inconel (which is like stainless steel) but Amco, which is a sort of bronze material. I got that mixed up in the above posts.

Eric

Glad you caught that. I started to write a response the other night questioning you about that but decided to let it go. You would have had a hard time cutting threads that easily in inconel. "Shavings" ha!