1127vf-lb Cross Slide Problem

[lpeedin]

About a year ago, the clamp down ring that clamps the base of the compound to the cross slide table, cracked, right in the middle over the sight window where you view the angle markings. This was the thinnest portion of the clamp ring so it figures that it was the weakest. I decided that I would drill additional holes in the clamp ring to utilize four bolts instead of the just the two it had from the factory. My thought was that it would help to even out the clamping pressure and then the crack in the ring wouldn't really be a problem.

Fast forward to this week. I finally decided to make a new beefed up clamp down ring to replace the cracked one. I took my time and hit all the dimension I came up with. I am really happy with how things turned out so far on the new clamp ring. I just need to mill out the sight window and drill the bolt holes and it is done.

The issue is, that when I went to test fit the new clamp ring on the cross slide table, I noticed that the sides of the t-slots are cracked and are actually starting to break and be pulled upwards. I am now fearful that I have broken my cross slide table and it has to be replaced. I have already spoken with Matt about it. Since I modified the clamp ring, this isn't really a warranty issue, and I'm ok with that. He is getting me a price on a new table.

What I was wondering is if anyone else has ever had this issue on their lathe, whether or not it is a PM lathe? I am actually thinking about making a new table now as opposed to getting another factory table. I do wonder how a table made from steel will wear on the cross slide made of cast iron? Any input would be appreciated.

Thanks,

 

[Bob Korves]

The only input I have, and you are probably already aware of it, is that the bolts have been tightened down too tightly. Usually on most Asian lathes the nuts strip out first, which saves the expensive parts. Not so on yours, I guess. It sure would have been easier to fix. The compound nuts do not need to be gronked down to keep the compound from slipping on the cross slide. It is good that you posted this here so others can be aware of the issues before it happens to them, too. Quality problem? Well, perhaps so, but we have to work with what we have or modify/repair/replace to get it back in service again. It is what I call NOB (nature of the beast).

 

[tmarks11]

On most lathes, the compound swivel ring is built directly into the cross slide, and bolts into it.

It looks like on yours it is on tracks, so you can mount the compound anywhere on the cross slide. Which is quite handy and clever, since sometimes when cutting bevels with the compound, you want to cut an angle and there is not enough travel in the cross slide to get the toolpost all the way back to accommodate the angle.

I was going to suggest you just through bolt your compound ring directly to the cross slide, but then you would lose the ability to reposition it. Still, if those t-slots are cracked, you could just bolt it in one position now while waiting for a new cross slide.

Something else you could do is mill two t-nuts that are about 3" long. That way it would spread the clamping force of the compound ring across more of the t-slot, and avoiding cracking it worse.

 

[Muskt]

3DShooter.
Your cross slide looks very much like those on the 9x20s. I had one for several years, & created a plinth & new T-Nuts for it.
Even though it would initially appear to be un-useable, I think that you can continue to use it with a bit of creative work. Tim's recommendation for the long T-Nuts would (to me) be spot on. I did a similar job on my 9x20 (even though I had an intact slide). Below is a link to my site showing the T-Nuts I created. You could do something very similar, and although the crack might continue or even break off entirely, you could fab some spacers to place on top of the T-Nuts shown in the center pic of the link. The spacers would need to be a few thous lower than the top surface of the slide, & would prevent the T-Nut from cocking while still allowing adequate locking force on the good side.
Just an idea to keep you up & running.

http://www.akpilot.net/T-Nuts/T-Nuts.html

Jerry in Delaware

 

[lpeedin]

Excellent feedback! I am aware on the larger lathes that the compound is usually located in a fixed position and that this design is a good way to add flexibility to the setup. I already have a new table on order with Matt. I really like the idea of the long t-slot bolts. I am thinking that I need to make t-nuts 4" long and then install threaded rod to match the hole spacing on the new clamp ring. I am going to run with that idea and continue to use it with the new cross slide table.

 

[lpeedin]

I got my new cross slide table yesterday direct from China. I love opening packages from other countries, btw. All was packaged fantastically. Everything appears to match the existing part, minus the cracks of course. I am going to get everything mounted up over the weekend and take her for a spin.

 

[tmarks11]

wow, that was fast!

 

[alan morris]

I noticed on my 1127 that the supplied t nuts for the top slide were slightly higher than the table surface when in the tighted state, I believe this was no accident, that they were ground to match the clamping ring and top slide so what happened to you would be prevented. If you make longer t nuts for clamping I agree with Muskt that the t nut height be adjusted to only allow a few thou clamping force.

 

[alan morris]

I have to correct myself here. I had stated that the supplied t nuts were above the table in the tightened position. When I went to my shop and looked they are in fact below the surface because of the guides on the bottom of the clamping ring. never the less they are still fitted to only have a few thousandth clamping force to prevent the cross slide table clamping slots becoming fractured and the clamping ring from warpage and fracture.

 

[lpeedin]

Tmarks, it was literally a week from the time Matt ordered it. Shipping wasn't cheap, but the option was to wait 12 weeks until his next shipment of machines arrived.

Alan, I have looked into machining new t nuts to do just what you are describing. I did note that on the factory clamp down ring, there was approx .022" of gap between the clamp ring and the table. I made the new with with .017" gap. I am actually thinking about putting it back on the lathe and taking another .005 - .010 of gap out of it. For now, I machined t-nuts that are each 4" long as the new clamp ring has 4 holes instead of 2. This should distribute the load a bit better. And I am now much more careful about how much i torque down the bolts.