Pm 1228-vf-lb Lathe Preparations

[John Hasler]

The zero on the dial is one of the marks that doesn't exactly line up with the half-nut engaged. Some of the other marks like up perfectly. :-\

That sounds like exactly what I would expect if you have the correct gear but the wrong dial face. You could make a correct face for it but IMHO this should be fixed under warranty.

 

[tmarks11]

Gunrunner you need to order a set of these for the Z axis hand crank. Bill did you just spit coffee on your monitor? :rofl:

View attachment 253356

 

[Franko]

I wonder if it would work like a regular thread dial if I made a new dial with 8 divisions?

 

[tmarks11]

I wonder if it would work like a regular thread dial if I made a new dial with 8 divisions?

Yes, I bet it would. But I would try cutting some threads before I spent the time to engrave a new dial.

In the near term, you could take a sharpie marker and highlight 4 divisions on your existing thread dial. Then try cutting the threads (maybe 13 tpi and 20 tpi) using the typical divisions that Doogie showed in the page he copied above.

 

[Franko]

This is really discouraging. I've gotten along fine never using one. Now, with a new lathe, I decide I should learn how and the instructions for the one I get are complete gibberish.

I think for it to work with an 8 line dial it needs a 32 tooth gear.

 

[ronboult]

Franko
My metric Lathe has 28,30,& 32 Tooth gears with a 12 division dial on a 3mm pitch leadscrew. It really seems like you have Chasing dial that is really designed for a metric lathe.





My mind can't quite get round whether a 28 tooth gear can work on a 8tpi LS for Imperial threads- I have enough trouble with metric which are really more simple.

Irrespective I think it will still work if you stick to just one start number say zero. Like tmarks11 says give it a go on a bit of scrap. Try several different pitch threads to convince yourself that it works. Not being able to use the other numbers just makes threading with your dial slower because you constantly have to wait for Zero to come round to start the next cut.

I really think that it is up to Precision Mathews to sort this one out. Goodluck
Ron

 

[DoogieB]

Did you count the teeth on the gear driving the chasing dial? If it's 28 teeth it's not going to work correctly if you have a 8 TPI leadscrew.

The teeth on the chasing dial should be a multiple of the leadscrew. So with an 8 TPI leadscrew, the chasing dial should be 8, 16, 24, 32... My SB 10K has a 32 tooth chasing dial. I think Atlas lathes use one with 16 teeth.

 

[tmarks11]

The teeth on the chasing dial should be a multiple of the leadscrew. So with an 8 TPI leadscrew, the chasing dial should be 8, 16, 24, 32..

Good point. For a 28 tooth thread dial to work, that would require a leadscrew pitch of 7 TPI. Otherwise 1 complete rotation of the dial will result in you not being exactly aligned with the thread for the next pass.

All this kind of makes me wonder if this is really a metric thread dial and wonder if the leadscrew is 8 TPI or if it is actually a 3mm pitch leadscrew (8.47 TPI).

The Grizzly manual for this lathe is confusing, as it tells you to install the Z28 gear on the thread dial for imperial, and the Z30 for metric. But than it says not to use the thread dial for metric and leave the leadscrew engaged for cutting metric threads. And than it says consult the chart for gears and thread dial positions for metric??!! So if you don't use the thread dial, why the chart for metric? And if this is for imperial, where is the imperial chart?

Poor Chinese translation of english documents leading them to manufacturer something they don't understand, and than (poorly) translate their faulty chinese translation back to english? Z28 used for some metric threads and Z30 for others seems more likely.

The Sieg C6 lathes have been very popular lathes for a long time (this is the grown-up version, the SC10). Grizzly sold a lot of copies of their version of the C6 combo machine (G0516). They didn't have a thread dial, but Little Machine Shop sells one, and from the pictures it looks (SWAG) like it has 8 divisions and a 24 tooth gear on it. The spec for this machine says 8 TPI leadscrew.

 

[tomh]

Franko
the instructions should have read= The imperial lathe will only use the 28T gear. align the dial to read 0 when using the chasing dial.
A lot is lost in translation
The 28T is the correct gear for cutting imperial threads.
Use the 0 mark only, and forget the other lines. As long as the 0 is close to the scale mark you will be fine.
I tell folks when learning to thread to focus on the ( 0 ) or #1 mark and not to use the other numbers or marks, because there is to much going on when threading that can mess you up as it is . Maybe this will help a little.

tomh

 

[tmarks11]

Use the 0 mark only, and forget the other lines. As long as the 0 is close to the scale mark you will be fine.

Which in reality is no different than the way I use my thread dial that has 8 major divisions. I still generally end up engaging it every single time at the same point, the "1" position just to avoid confusion. This works for any even or odd threads (but not fractional, but I have never cut any so who cares).