Metric threads on Heavy 10

[motor mark]

I am new to posting on this forum, but I have watched and learned from this site over the last year. Most answers I needed were already here. I couldn't find an answer to this, so ....I have an older single tumbler 10L and need some advise on what gears to use for cutting metric threads. Any help is appreciated. Thanks

 

[garyphansen]

Depending on which metric threads you are talking about, some can be approximated with what you have in your gear box. It all depends on how much thread ingagement you have. You might get away with threading on a real metric nut on your fake metric threads, but if you need to use your fake metric threads in a deep hole your are out of luck. The only way to cut correct metric threads is with a metric transposing gear added to the gear train. On the banjo. The metric transposing gear is two gears fixed togeather, one is 127 tooth ant the other is 100 tooth. I think they are going for close to $300 form sone company that makes them. (I might be able to find out for you if you want.) From LaBlond who knows how much. They priced an eighty tooth for my 9" last week at $256. plus shipping. Gary P. Hansen

 

[peterh5322]

"The metric transposing gear is two gears fixed togeather, one is 127 tooth ant the other is 100 tooth."

There are forty or so good approximations to 100/127.

Martin Cleeve's book "Threading in the Lathe" details them all.

Sadly, even with a true 100/127 transposer, a number of stud gears will be required to cover all useful metric pitches.

The metric threading kit for my Logan includes the 100/127 transposer and eight or so stud gears to cover all standard pitches.

An Imperial QC box wasn't designed with the right ratios for metric pitch increments.

 

[motor mark]

That points me in the right direction. Thanks

 

[jim rozen]

The hard part of metric transpose gears (I bought my set from dave ficken *right* before he closed up, it may be the last thing he sold) is figuring out how they are supposed to work!

After a good deal of headscratching, I realized that that the thread that is cut is:

20 divided by TPI (on QC box) = Pitch in mm

This is for a *double* tumbler QC box, so I'm not sure it covers single tumbler ones as well.

So I can cut, say, one mm pitch threads now simply by setting my QC box at 20 tpi.

But as has been pointed out, there are some mm pitches that still require additional change gears with the transpose pair.

Jim

 

[peterh5322]

Most medium sized lathes use 16 D.P. 14-1/2 P.A. change gears.

Boston Gear makes 16 D.P. 14-1/2 P.A. change gears in every tooth count from very low to at least 128, including the all important 127 and 100.

(You may have to bush the bore for your particular machine).

For smaller machines, or for special applications, you may want to use 20 D.P. or even 32 D.P.

The "end gear" unit of the Monarch 10EE, for example, is totally enclosed in an oil bath, which imposes severe size constraints. A 127 tooth metric transposer of 32 D.P can be accommodated, but not one of 16 D.P, which is otherwise the standard pitch of all the gears in the "end gear" unit. Therefore, a compound gear of 127 T, 32 D.P and 60 T, 16 D.P. is part of the 10EE's metric transposer. "End gears" of 45, 50, ..., 75, 80 T, 32 D.P., complete the 10EE's metric threading kit.

 

[motor mark]

Would you have contact info for boston gear? Thanks

 

[garyphansen]

Motor Mark:

I believe the gears on your South Bend ar 18DP gears and Boston gear does not make them. Could be Wrong!
Gary P. Hansen
ENGINEERING DRAFTING SERVICES

 

[garyphansen]

Jim Rozen:

The metric transposing gear chart on the Wall Gear Charts I am selling (see the ad section) show 33 different metric pitches from .20-6.00 MM can be cut using the metric transposing gears and one of six different stud gears 48,44,40,36,32,and 28 tooth. The chart info. was sent to me by davethegundoctor. and showes what settings to use on the quick change gear box to get which pitches.
Gary P. Hansen
ENGINEERING DRAFTING SERVICES

 

[garyphansen]

Jim Rozen:

The metric transposing gear chart on the Wall Gear Charts I am selling (see the ad section) show 33 different metric pitches from .20-6.00 MM can be cut using the metric transposing gears and one of six different stud gears 48,44,40,36,32,and 28 tooth. The chart info. was sent to me by davethegundoctor. and showes what settings to use on the quick change gear box to get which pitches.
Gary P. Hansen
ENGINEERING DRAFTING SERVICES

 

[morsetaper2]

The South Bend Lathe book, "How to Run a Lathe" has information on setting up the transposing gear sets for their lathes. I have a heavy-10 (dbl tumbler) w/ the transposing set. Here are some pics if they help you:

Mark

 

[motor mark]

Thanks for the photo, it helps a lot. Now I guess I need to find the gear set.

 

[garyphansen]

Morsetaper 2:
Could you measure the O.D. of the 127 tooth gear and the 100 tooth gear for me? I can figure out the O.D.s with a little engineering but have found that South Bend gears do not always match what the engineering says they should. I am planning to try to make the gears. Trying is the key word. I have the proper cutter coming. But have not figured out how I am going to index them and cut them on my lathe.
Gary P. Hansen
ENGINEERING DRAFTING SERVICES

 

[modscoot]

garyphansen What is the D.P.of these geard 18 or 16 ??

 

[garyphansen]

The gears for a South Bend 9" lathe are 18DP.

Gary P. Hansen
ENGINEERING DRAFTING SERVICES

 

[morsetaper2]

Morsetaper 2:
Could you measure the O.D. of the 127 tooth gear and the 100 tooth gear for me?

100 tooth: 6.366-6.368 inch
127 tooth: 8.056-8.058 inch

That is the range of OD measurements I got w/ an 8" dial caliper with measurements taken at 4 or 5 places about the OD's.

mark

 

[garyphansen]

Mark:
Thanks a lot!
Gary P. Hansen

 

[hms50]

Good morning Gentlemen,
Just for what it may be worth:

According to my local Boston Gear vendor, they no longer make gears in 18 DP. For that matter, he could not find anyone who did. I just found this website, rdgtools.co.uk that sells 18 DP gears for the Boxford lathe. My understanding is that this is a clone of the South Bend. They list all the gears needed including the 127/100 tooth compound. I've contacted them and asked for prices in U.S. funds. If I understand their online catalog, their prices don't seem too bad. To cut the complete metric conversion set one would need at least three gear cutters. As I already have two of them, it may be cheaper to make them myself instead of buying them. But for somone without any cutters or an indexer and mill, this might be a way to go.
hms50

 

[garyphansen]

On a previous post I stated the 9" South bend uses 18DP gears. I should have also stated the heavy ten South Bend uses 16DP gears. Hope I did not mess anyone up.

Gary P. Hansen

 

[armen]

Dumb question-
What does "DP" stand for in relation to gears?
thanks,
-A