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Roger_H
01-22-2012, 12:28 AM
This is the plate on the lathe and I can not figure out how to set it up for 40 TPI. The lathe is new to me and didn't come with any paper work.

Thanks.

http://i1208.photobucket.com/albums/cc366/rheatherly1/IMG_20120121_064045.jpg

LKeithR
01-22-2012, 12:48 AM
Post some pics showing the handle layout as well and someone can probably help you figure it out...

lakeside53
01-22-2012, 12:59 AM
First you'll need to make sure your have change gears "a" and "b" both with 60 teeth, then it looks like you just select 1 and V and B, whetever that means with your levers.

camdigger
01-22-2012, 06:10 AM
A picture or description of the lathe itself would help.

There are 2 obvious (to me) hints... The lathe appears to have a SAE/English/non-metric lead screw. It also appears to have been provided with a 127 T change gear for metric threading. Here's what I would suggest:

1.) make sure the change gear train is as per the diagram above the table (NOT as appears below). Make sure the spindle gear and the lead screw gear have the same # of teeth.

2.) It appears that there are 4 controls on your lathe's gear box that control the speed of the lead screw vs the spindle speed. IE 2 levers and 2 knobs. Do the levers and knobs have labels? The levers likely have a series of detented postions each of which gives a specific ratio. the knobs likely have only two positions at 180 degrees to each other. If the knobs are labelled, it is a simple matter to go to the table and figure out the combination of lever and knob positions to give the desired TPI of the thread.

3. the threadding controls are usually on the lower half of the headstock the levers on the top half control the spindle speed. Here's a picture of a lathe with 4 knobs.
http://i766.photobucket.com/albums/xx301/camdigger/C0636A20headstock.jpg

Tony Ennis
01-22-2012, 09:01 AM
then it looks like you just select 1 and V and B

I think we're missing the 2nd knob setting on that.

So gears a and b have to each be 60 teeth, which limits the choice to 2 or 3 columns, can't quite tell how many.

Then choose levers 1 and V to limit the 2 (or 3) columns to exactly one column.

There are still four possibilities (5, 10, 20, and 40 TPI), one for each row in the column.

Set knob positions B and C which uniquely selects one of the 4 rows from the bottom. In this case, 40 TPI.

If you wanted a 13 TPI thread, you'd put on 40 and 52 tooth gears, choose levers 1 and V again, and set knobs to B and D.

That's a total guess. Caveat Emptor.

Roger_H
01-22-2012, 03:08 PM
Thank you, I'll go check the change gears in a little bit. My lathe looks just like the picture camdigger put in this thread.

camdigger
01-22-2012, 03:15 PM
Thank you, I'll go check the change gears in a little bit. My lathe looks just like the picture camdigger put in this thread.


A google search for the company name on the lathe name plate will turn up their web page. Their sales or service department may be willing to provide a manual for your lathe.

As far as I can remember, Modern Tool is importing from Taiwan like so many others including guys like Jet. Is there a company name on the machine's info plates anywhere?

Roger_H
01-24-2012, 05:24 PM
OK, I found the 60 tooth gears in the box. the large gear on the lathe reads 127 tooth. I assume that I can take the large one off and flip it over since it is large on one side and small on the other for the 120 tooth gear? Or do I just make sure the teeth engage the smaller side of the large gear?


Thanks, it is making more sense, but the transalation of the tiwaniese to english leaves a lot to be desired.

Carld
01-24-2012, 06:10 PM
I am thinking the change gears have a shoulder on them equal to the width of the gear. If that is so just flip the gears over so they are riding on the 120 tooth gear. If no shoulder then you may have spacers to use.

Oldbrock
01-24-2012, 06:48 PM
It makes no difference whether the idler is 120 or 127 as long as it is a simple gear train, not compound as in the bottom pic. The idler does nothing except make sure the driver and driven gear turn the same direction and fill up the space between driver and driven gears. As long as the driver and driven gears are the same, could be 50 and 50 or 100 and 100, in your case 60 and 60 with a gear of any number in between it will give the one to one ratio required. Now set the four dials on the qcgb as indicated. Peter

Jim Shaper
01-24-2012, 08:14 PM
You need the 127 engaged for metric threads where it changes the compound ratio. You can see that in the lower image.

tdmidget
01-24-2012, 08:49 PM
Come on, look at the chart. A should be 40 teeth and B should be 44. The 120 or 127 tooth is what changes from English to metric.

Carld
01-24-2012, 10:17 PM
That's wrong tdmidget, the chart clearly shows for 40 tpi a=60 and b=60 with the 120 gear between them but he could use the 120 or the 127 for an idler gear.

tdmidget
01-24-2012, 10:41 PM
Nope. ALL english threads are cut with a 40 teeth and b 44 teeth. The center gear is 120 teeth and both mesh with the 120 tooth part. The rest is in the controls that , for some reason, we have not seen.
For metric a meshes with the 127 and b with the 120. Again we have not seen the rest of the controls.

platypus2020
01-24-2012, 11:00 PM
Thats just like my Jet

gear A - 60 teeth

gear B - 60 teeth

levers in #1, V, B, C



http://i805.photobucket.com/albums/yy339/platypus-20/IMG_20120121_064045.jpg

Roger_H
01-25-2012, 08:28 AM
Thank you for all the help. I will take that picture of the levers tonight, I figured since it was just like the one camdigger posted I wouldn't need to. This is all new to me and the pictures don't really help until after you start to figure it out. I see now that my main gear with the 127TPI marking facing out, has the 120TPI gear on the inside. Now I'll install the two 60 TPI gears and set the levers and have a go at it. That will have to wait until after my day job.

camdigger
01-25-2012, 04:48 PM
One last suggestion Roger - invest the $5 - $7 for a thread gauge. It will save you some time and aggravation...

Alternately, learn the goobledygook on a fish tail template (which you should look at as a practical present for SWMBO on whatever occaison)....

Roger_H
01-26-2012, 07:52 AM
Alright, I went out to snap the picture, but got side tracked putting the 60 tooth gears in and seeing what happens. It is all working, well almost, the thread indicator thing does not turn. I think it might just be frozen up some. I'll take it apart this weekend and see. I have a thread gauge and the fish scale thing already. Now I just need to decide on which tool to use for thread cutting. I want to go with an insertable tool holder and avoid having to grind my own right now.

PixMan
01-26-2012, 08:37 AM
I would advise learning to grind a tool is something that would help you in the long run. If you don't have a bench grinder with a fine wheel, that makes things a little more difficult.

If you absolutely want to buy a pre-made threading tool, I'd suggest you instead look to the pre-ground HSS tools such as that in the Aloris No.8 holder. With those, you grind only the top and it always maintains the 60 shape perfectly. The HSS will hold up better under the extremely low cutting speeds you are likely use in starting the learning process.

As for the threading dial not moving, that's rare for it to be frozen-up. Is it's lower gear engaged in the lead screw's thread, and is the lead screw actually turning? On smaller machines that use a single keyed lead screw instead of separate lead screw and feed rod, it's common practice to disengage the threading dial so it doesn't spin wildly when turning at higher speeds than you would ever use for threading.

On machines with the separate lead screw and feed rod, the threading dial only turns when the lead screw is engaged and turning. If you have the lead screw turning, the threading dial will stop turning the moment the half nut is engaged and the carriage starts moving.

Jim Shaper
01-26-2012, 10:37 AM
The aloris threading tool is the bomb. Very glad I own one.

camdigger
01-26-2012, 10:43 AM
I would advise learning to grind a tool is something that would help you in the long run. If you don't have a bench grinder with a fine wheel, that makes things a little more difficult.

Grinding your own threading tool is an admirable goal, but one step at a time...


As for the threading dial not moving, that's rare for it to be frozen-up. Is it's lower gear engaged in the lead screw's thread, and is the lead screw actually turning? On smaller machines that use a single keyed lead screw instead of separate lead screw and feed rod, it's common practice to disengage the threading dial so it doesn't spin wildly when turning at higher speeds than you would ever use for threading.

On machines with the separate lead screw and feed rod, the threading dial only turns when the lead screw is engaged and turning. If you have the lead screw turning, the threading dial will stop turning the moment the half nut is engaged and the carriage starts moving.

Some lathes (like mine, and possibly yours) actually have enough play deliberately machined into the threading gear mounting holes to allow the gear to be disengaged from the lead screw while doing other work on the machine. Engaging the drive gear with the lead screw may be as simple as loosening off the mount screws to shift the housing. If the lead screw is not turnong (and consequently not turning the thread dial) look ofr a shear screw in the lead screw drive.

Roger_H
01-26-2012, 10:57 AM
I'll check more Friday night. The lead screw is turning and when I look at the thread dial I can see the gear in it is not touching the lead screw. The carriage will move when I engage it though. That is why I figured the dial was frozen or just needs adjusted.

camdigger
01-26-2012, 12:49 PM
......I can see the gear in it is not touching the lead screw................

Ding Ding ding ding. We have a winner!

Should be a simple matter to swing the whole doodad over to make the gear engage the lead screw.

Roger_H
01-31-2012, 06:51 PM
Ding Ding ding ding. We have a winner!

Should be a simple matter to swing the whole doodad over to make the gear engage the lead screw.


OK, so when I swing the thread dial over to contact the lead screw the gear still does not turn. I took the whole dial off and took the nut off the bottom to loosen the gear in the thread indicator. Now the gear engages and turns, but the number dial does not move. What else can I take out of this thing to check?


Thanks.

J. Randall
01-31-2012, 10:16 PM
Should be pretty easy to check, the gear has to be fixed to the shaft, that in turn spins the dial on the other end of said shaft. With leadscrew turning and half nuts disengaged, the dial should be turning. When the leadscrew is turning and the half nuts engaged, the dial should remain stationary on what ever mark it landed on.
James

Roger_H
02-01-2012, 07:40 AM
I took the assembly apart and the gear is not fixed to the shaft anyway, but the nut and spring washer. Any ideas on how to fix that little problem? I went on and cleaned up the shaft and hole so it would rotate, but I'm not sue about how to pin the gear.

PixMan
02-01-2012, 08:39 AM
Pictures would go a long way here. I find it hard to believe that the threading dial's gear, usually made from brass or bronze, would have no means of fixing it to the shaft I would think a roll pin, a woodruff key, a standard key or some other means would have been used by the factory.

I would find a roll pin small enough to fit between teeth on the gear, drill though, add pin. Just make certain that the length fo the pin is just barely shorter than the root diameter of the gear teeth.

Roger_H
02-01-2012, 08:52 AM
This is the exploded diagram of a similar machine http://www.grizzly.com/products/G0709/parts/1
Part 525(dial indicator) goes into the housing part 537 and has gear 538, washer 539 and the nut 540 holding it on. Nothing else on there.

RussZHC
02-01-2012, 09:36 AM
Gotta go with Pixman here...there should be some sort of mechanism similar to the options he mentions...BUT I supposed it could be the case it relies just on the pressure of the nut and spring washer against that bolt shoulder to hold the gear in place and tight enough when engages that it does not just spin on the shaft (without turning the shaft and from there the actual indicator on top)...if that is the case, IMO, the design is a bit problematic...I'd add a pin

Roger_H
02-01-2012, 09:41 AM
Yeah, when you tighten the nut enough so the gear does not just spin on the shaft, it is then too tight to turn the dial. I was thinking of adding another washer or maybe even a thrust bearing (if I can find one that size) between the gear and the housing to help it turn. I might just drill it for a pin and be done with it.

PixMan
02-01-2012, 09:42 AM
I just pulled up the PDF-format parts manual for my lathe. The threading dial on the 1974-vintage Victor 1640 has a 3mm x 13mm key to keep the pinion gear from slipping on the shaft.

Roger_H
02-01-2012, 09:52 AM
I could cut a keyway into it since I have the cutters already.

Al Messer
02-01-2012, 05:58 PM
And after you have the proper gears set up, try it on a piece of SCRAP first!

Al

Roger_H
02-01-2012, 09:27 PM
Got it. I took the shaft out of the housing (bugered up the threads) cleaned it all out, found the 8 X 1.25 metric die and fixed the threads, reassembled things and installed back on the lathe and it is working fine. Did a test cut on some cold rolled steel and it looks perfect and matches up to the thread gauge. Thanks for the help.