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NeoMoses
04-22-2003, 05:34 AM
Has anyone here used moglice to reduce the backlash on their acme screws? I'm playing around with a mill/drill that has about 0.015" backlash on the X and Y axes, and would like to get that down to less than 0.003" backlash. Is moglice capable of doing this? Also, where is a good place to buy it?

HuFlungDung
04-22-2003, 10:46 AM
What the H is moglice? :)

castguy2003
04-22-2003, 12:47 PM
Originally posted by HuFlungDung
What the H is moglice? :)

:rolleyes: Glad I'm not the onlydummy out here.:D

wms
04-22-2003, 01:04 PM
You use it to "Residually Magnetize a Flambo Joint". :rolleyes:

cncadmin
04-22-2003, 01:05 PM
I know what it is geezz I thought I was dumb to , (just kidding) I did a search and what it is, is


Moglice FL/P Formulation Date 1988 - is a fluid with a consistency similar to gear oil. It can be injected or poured to produce way systems, quill bores, nuts or tapers. It is also used in the pour and set application technique.
Moglice P-500 Formulation Date 1986 - is a slightly thicker fluid with a consistency similar to honey. It is still injectable and is often used in ball nut applications, air bearings and in the production of sub-micron accurate bores.

Moglice 628 Formulation Date 1985- is a semi fluid having the consistency of a thin putty and tends to run on a vertical surface with minimal damming required, but will not run off a flat way. It is most commonly used on machines with large flat ways because it is easier to mix, apply and get the component down and aligned.

Moglice Putty Hard Formulation Date 1983 - is a no-slump putty and is the most common material used on standard way systems. It can be applied to vertical or overhead surfaces without running or dripping.

Moglice 1000 Fluid is a fluid about the same viscosity as the Moglice P-500 above. Moglice 1000 Fluid differs in that it contains Teflon and results in a 25% to 30% further reduction in friction. It also provides added protection against moisture absorption.



Here is the website - http://www.moglice.com/

HuFlungDung
04-22-2003, 01:28 PM
Sounds like wishful thinking to make it absorb backlash. Its probably viscous as dickens and makes the screws difficult to turn.

If you are trying to reduce the backlash in a standard Acme thread, it would be better to face off one side of the existing nut (or the casting, etc), cut a new thread in a disk that you can fasten to the face of the old nut. Then, shim this disk away from the face of the existing nut until you have reduced the backlash.
Use bearing bronze or aluminum bronze (best but toughest to cut) to make the nut.


Another method involves splitting and then finding a way to collapse the threads of the existing nut, but this the least desirable method because it tends to pull the screw offcenter, especially when you get near the extremes of travel.

balsaman
04-22-2003, 01:29 PM
Oh, Thaaaat Moglice....

:)

Eric

NeoMoses
04-22-2003, 07:31 PM
Originally posted by HuFlungDung
Sounds like wishful thinking to make it absorb backlash. Its probably viscous as dickens and makes the screws difficult to turn.


It's only viscous so that you can pour/mold it into the shape you want. It's not a liqid that "absorbs" backlash. It hardens and becomes a solid, thus forming new threads. From what I've seen, many people have been successful at getting their backlash down below 0.002" with it, so I'm gonna try it.

I've contacted Devitt Machinery, and they answered all of my questions well. I'll be purchasing some moglice and using it this weekend. It should cost less than $100, which seems very fair to me.

I'll let you guys know how it goes, since it seems there's not many around here who have heard of it.

HuFlungDung
04-22-2003, 07:58 PM
Yes it will be interesting to see how it turns out. I didn't understand that is what it does. But, this begs the question, how do you make it give you the tiny bit of clearance that you need to get the screw out of it after it hardens up? Spray paint the screw first perhaps to try to achieve the thickness of the paint skin for clearance?

wms
04-22-2003, 08:26 PM
Hu,
I Thinks the stuff "shrinks" a little as it hardens up, hence your clearance. Ah the magic of chemicals.:D

HuFlungDung
04-22-2003, 10:38 PM
Could still be tricky in the narrow confines of a nut, where the thickness of the injection is only going to be .007 to .015. I'd be surprised if the bond is super strong to the one surface, and yet provides clearance on the other. It is very difficult to even clean a nut to be chemically clean enough to provide a good bond without some kind of acid etch. Then to also provide a non contaminating release agent on the screw, and get it into position without contaminating the interior of the nut would be miraculous.

I think that for the method to work, you'd almost have to saw the top half off the nut, then bolt it back down for the duration of the procedure, then open it up to release the screw again.

But, anyway, we'll sit and wait for the play by play.

NeoMoses
04-23-2003, 07:07 AM
Here's the basic procedure as I understand it. (I've never done this before, so this may not be correct).

Remove acme nuts from leadscrew(s)
Bore out acme nuts, about 1/8" oversize.
Thoroughly roughen nut surface, then clean well.
Clean acme screw very well, then apply release agent.
After release agent is in place, slip acme nut over screw and inject moglice.
Let sit overnight, allowing moglice to fully cure.


The release agent dissolves in oil, thus giving you the required clearance with minimal backlash. If clearance is too tight, use lapping compound to increase the clearance. Like I said, I've never done this, so there may be some errors in what I just said. Hopefully I'll know for sure after this weekend.

NeoMoses
05-02-2003, 05:25 AM
Just an update. I bought a 100g moglice kit from Devitt machinery after talking to them on the phone. They are very helpful. Entire kit was about $100 with shipping.

Last night I tore down the mill and removed the Acme leadscrews and nuts. After a good washing in the parts washer, they're now ready to be prepped for moglice. Basically, you need to bore out the acme nuts about 0.060" or so, then cast new nuts with moglice in the existing bronze.

Just a couple of good things about moglice:
1. It's longer-wearing than bronze.
2. has a lower coefficient of friction than bronze.
3. According to Devitt, 0.001" backlash is achievable. I'll let y'all know if this works out for someone who's never done it before.

I should be boring out the nuts and possibly casting the new ones tomorrow. If all goes well, I should have the mill put back together and running sometime this weekend.

Is anyone here interested in me writing a tutorial and documenting the entire process?

cncadmin
05-02-2003, 07:35 AM
Originally posted by NeoMoses

Is anyone here interested in me writing a tutorial and documenting the entire process?

YES and put it in the "user review section".

NeoMoses
05-05-2003, 11:42 PM
Update: casted the new nuts this weekend. Everything went as expected, but they are both pretty tight. Ordered some lapping compound today from Devitt, so hopefully I'll have them running smoothly by Wednesday.

Right now, with the nuts very tight, I'm seeing about 0.0001" backlash on my X axis and about 0.00075" on my Y axis. I think the majority of the problem on the Y is located in the bearing, not the nut. (Note the about in the previous sentence. My dial indicator only reads to 0.001". I may be able to borrow a more accurate one soon, though.)

Hopefully I can get these running smoothly without introducing more than 0.002" backlash on either axis. That's my goal.

More updates and a full review to come!

paulried
05-06-2003, 12:30 AM
I wonder if the Six-Million Dollar Man had the problem of "tight nuts". Sounds like it would be difficult to sit down.

Sorry, I just couldn't resist. I think I also just revealed my age by admitting to watching the show! "We can rebuild him...better...fast..."

NeoMoses
05-07-2003, 07:56 AM
The 6 million dollar man can sit down now. After lapping, the nuts are just as smooth, if not smoother than before. Backlash is about 0.004" on the Y axis and less than 0.001" on the X! Not bad for about $160 in materials and a couple days work. Looks like this stuff performs like it is advertised. Complete writeup should come within the next couple of weeks if I ever stop playing in the shop:)

HuFlungDung
05-08-2003, 11:28 AM
Glad to hear that it worked out well for you. How much trouble did you have aligning the screw inside the nut when making the casting? Were you able to "cast it in place" to make this easy to do?

cncadmin
05-08-2003, 12:51 PM
Originally posted by HuFlungDung
Glad to hear that it worked out well for you. How much trouble did you have aligning the screw inside the nut when making the casting? Were you able to "cast it in place" to make this easy to do?

You're back?? We missed you. :D

wms
05-08-2003, 01:04 PM
I second that.
Tell us about your Holiday.:D

NeoMoses
05-08-2003, 01:06 PM
Originally posted by HuFlungDung
Glad to hear that it worked out well for you. How much trouble did you have aligning the screw inside the nut when making the casting? Were you able to "cast it in place" to make this easy to do?

I wasn't able to cast it in place. I ordered some 0.010" and 0.001" shim stock and cut very thin strips. I then supported the bored out nut at 4 places on each end to center the screw inside the nut. It worked out OK. If I had a lathe, it would have been nice to make a custom bushing, but alas, no lathe lives in the shop:(.

cncadmin
05-30-2003, 03:40 PM
How is it holding up?

ger21
05-30-2003, 06:09 PM
As an alternative to moglice you might want to check out.

http://www.phillycast.com/.

Look under Super Alloy. I'm waiting to hear back from them on pricing info.


Gerry

NeoMoses
06-01-2003, 07:00 PM
Originally posted by CNCadmin
How is it holding up?

It's working very well. I'm very happy with the low backlash and smoothness.