[subnoize]

Hello Everyone!

I just wanted to announce yet another successful X3 conversion using the CNCFusion.com deluxe 5mm ballscrew kit. See an image at http://www.planecnc.com/hdr_00013_0.jpg

My X3 is a Grizzly variant. I have a Sherline 4" rotary table for my 4th axis which still needs a mounting to be of use (can you say, "first project?").

Electronics are by Probotix.com. They are wonderful people and the have a great deal of knowledge on the X3 conversions. They built my system and put it in a nice little box so once I get everything calibrated and "installed" into my shop it will all look very pro!


- snz

[H500]

Looks good! The fun begins. It's easy to get addicted.

How much backlash do you have on the Z axis?

[subnoize]

How much backlash do you have on the Z axis?

Actually, backlash doesn't seem to be all that great on any of the main 3 axis. The ballscrews and nuts are really nice. You truly get what you pay for. The Sherline rotary has the only backlash I can actually see at the moment (and that was expected with a worm drive), but give me time to get everything calibrated. You can't make a system without backlash so its in there!

Now, what is bugging me is the z axis belt drive slipping! I'm trying to figure if I have the belt too tight or too loose. I know on the belt driven tail rotor on helicopters you actually have to have a considerable give or you shred belts like toilet paper. Now, does this hold true here or is that only with high speed belts? Maybe slow belts need to be tighter? Then again, there could be something to the gas piston everybody attached to the head on these things! I could be running the stupid thing at too high a feed rate?

Well, I guess these are questions for CNCFusion!

So, no, no visible backlash but I'm still testing and will go through about a month of tuning and then I can tell you within 0.00005" over a 10 " distance what the backlash to is...but for the moment I'm happy with everything but the belt drive!

PS. Also, X3 have a problem with the head moving because of the four screws that hold it to the base work loose, which would appear as backlash. The solution is to retorque the bolts every so many hours of operation. I think that is one of the biggest week points in the X3 design. That said, try to find better for the price!

[H500]

My Sx3 has about .005" of Z backlash. I believe it's caused by the head pivoting on the poorly machined gib whenever there's a direction change. I will correct the problem when I get around to it.

HTD timing belts tend to have some backlash. The more expensive GT type is supposedly backlash free. Both needs to be tightened properly. I assume you're getting around 100ipm on the Z. That's easily handled by the belt.

[subnoize]

Oh, I'm sure I have loads of backlash that small on every axis. I was thinking you were talking about something greater than that. I paid less than $3,000.00 so if it does 1/10th of what I ask of it I'll be happy. I never was expecting very much other than to learn the hard way, right?

Well, the guy from CNCFusion wrote me back and said to use a crowbar to pull the belt as tight as possible so that puts that part to rest.

I guess my long running project will be building a better CNC using the prior machine, right? Maybe after the third or fourth generation I'll truly have what I want.

[H500]

You probably have a pretty good machine already. All that is required is to fine tune it carefully to get the most out of it.

I certainly would take the crowbar advice with a grain of salt. The Gates timing belt manual should have the recommendations for the belt tension.

[subnoize]

I certainly would take the crowbar advice with a grain of salt. The Gates timing belt manual should have the recommendations for the belt tension.

The little 18" crowbar worked wonders! You can't get it tight enough by hand. All you can do is get it tight enough where it won't slide back and use the crowbar to pull it out to the correct tension and then tighten down the screws. It looks to be the opposite of helicopter belt driven tail rotors. Helicopter are very high speed whereas this is low speed but high torque.

My z axis doesn't make any noise now but you do get this deep rumble through the floor when the head moves down. You can't hear it but you sure as hell can feel it.

[dogmeatk]

This seems very odd to me. I tightened mine down by hand and have had no issues with the Z axis at all ... don't even have the gas strut. I havent had any problems with head movement on mine either, even after a few crashes :X

I have the Grizzly variant, as well .. guess quality control is all over the place on these?

[dogmeatk]

Oops! Just saw the pic and noticed you had an X3 and not the SX3 .. disregard my head movement comment!

[subnoize]

Oops! Just saw the pic and noticed you had an X3 and not the SX3 .. disregard my head movement comment!

Actually, only your head assembly is different. The z axis is the same on your sx3 as on my x3. Besides the bigger motor and tilting head they are suppose to be identical. You just paid more for that extra wobble from that tilting head ;-) You can upgrade later to a brushless motor for much less than getting it included on the mill but you retain the rigidness of the head. That also gives you spindle control without having to screw around with the existing electrics.

Truth is, these mills are hand made, no two are alike. I've heard older folk refer to them as "snowflake mills"...

Everything is crooked on mine, but that just gives it character! It has personality! Its not just a hunk of cast iron anymore!