PM-1130V Thread Table

[JPMachine]

Hello!

New here, I'm excited to learn a bunch. I currently have some mini equipment that works well for what it is. I have a fully accessorized PM-1130V on order for mid-late September arrival. Super excited about that.

One question I have is for threading. The table in the manual does have every real thread anyone would ever need... but what about all the possibilities? I see some tables here for the 12 and 13" lathes, but nothing for the 1130V yet so I am trying to figure it out.

Why, You may ask?

Well I use my lathe to custom wind springs!

The springs above are with my change gears set to 3.5 TPI.

For my current lathe, a hi-torque 5100 7x16 lathe, little machine shop has a handy change gear calculator to get practically any thread pitch.


Note that it DOES have an entry for other lathes...
I have made good progress in determining that the gearbox ratio is 1:1 for speed B, 2:1 for speed A, and 3:1 for speed C. With that, i was able to generate a table that always appears with "B" selected... With A, you just multiply by 2, with C you just multiply by 3. Pretty simple.

What I do not know, since I dont have my lathe yet, is their A-B Min, A-B Max, etc. So when it generates a list of possible gear changes, it includes a lot of setups that would not be physically possible. Does anyone have these numbers?

Has anyone made a change gear chart for the 1130V yet?

Thanks!

 

[Just for fun]

Welcome to the forum JPMachine! I don't have the answer you are looking for but there are a lot of smart guys here, my guess someone will have the info you are looking for.

There is a guy on here Dave @B2 that may be able to assist. He has a really in-depth spread sheet on threading that covers mostly the larger lathes.

 

[markba633csi]

The 1130v manual has the tables for power feeds and threads, check PMs website
(file too large to post here)

 

[B2]

Hi @JPMachine

As @Just for fun suggested, I wanted exactly what you are after fro my lathe, PM1440GT, and so I built an Excel Workbook that finds the TPI etc. values for almost any set of gears (external and internal) for almost any lathe. The macros that I wrote for Workbook takes the individual lathe's sheet and steps through all possible gear combinations to generate a table of all possible TPI, feeds, imperial and metric values. This table can be massive if you have a lot of external gears available! Of course you can also experiment with gears that you do not have to see what a new gear would provide. Other macros search the table for specific values, or approximations to values and can generate a second table of possibilities for you.

The workbook already contains a few lathe models, but I don't believe I set one up for the PM1130V. Usually figuring out the gear box train is the most difficult for folks but in the 1130V this is not a problem. There are only three lever settings (1x, 2x, 4x) plus the power feed Vs. leadscrew lever so this is simple. The set up for the external gears is also very straight forward. The only issue here is what gears will physically fit on which axes and will touch its neighboring gear. If the saddle travels both via a Feedbar and a lead screw then TPI values can be obtained for both. Understanding the gearing at the saddle is then needed. Cross feed rates listed on lathe tables are not always accurate, but with some effort values from the spread sheet calculations can correct for this.

You will find the recent version Excel workbook at:

Re: Improved Version: TPI, Feeds, X-Feeds: Generalized Lathe TPI Excel file: "TPI_ManyLathesRev1 N502_1630"

There was an earlier posting of this work, but the macros are not nearly as powerful and the individual lathe spread sheets are laid out a little differently. The earlier version of this is linked to the above.

So, I am taking a quick look at the 1130V manual. And I see that there are the following external gears available:
20, 25, 30, 40, 45, 50, 55, 60, 63, 65, 70, 75, 80, 80. It appears that the axis shafts are all the same diameter so the natural assumption would be that any gear could fit on any shaft. However, this may not be physically viable. One can only tell be measuring the positions. Never the less, the work books general approach is to assume that they are all physical and then allow the lathe operator to eliminate the ones that are not. Fortunately, when there is a diverse internal gear box, there are commonly multiple gear arrangements that will yield similar results.

I will take a look at your lathe and see if I can make a trial spread sheet for you.

Dave L.

 

[Weldingrod1]

I built a spreadsheet for my Hardinge like this. I searched for both exact threads and also for "very close" threads.

You will run into some geometric challenges on the studs and banjos. For a given minimum center to center distance you can translate to a minimum functional tooth count. So, if you want a 20 tooth on one stud, you can calculate the minimum mating tooth count. Easy enough to teach this to your spreadsheet or, just make a chart with all the possible combinations and X out the ones where you find it can't be assembled... like I -actually- did!

Sent from my SM-G715A using Tapatalk

 

[B2]

Hi @JPMachine

Ok, so I went down this rabbit hole .... and I made a pass at building a spread sheet for the PM1130V. It is attached, but without any of the macros as posting at HM with macros is not allowed unless you zip the file and hide them. So it is of limited value as choosing values is rather tedious. Never the less, the results will confirm anything you are guessing about. However, you can use the pull down menus to select different gear values for the different positions to generate the TPI (Imperial or metric) values. If you come back to me and tell me if you think the spread sheet is working for your lathe and I can put the sheet into the workbook with the macros and post it so that we can generate a full table of all possible thread values.

Included is the ReadMe sheet to provide a bit of description of the spread sheet layout.
See Cells at Row 30, Columns M-V. I left these set up to generate the 32 TPI value. So before you change the gear settings compare the columns of gears to the manual so that you will know which columns correspond the manuals notation of Z1, Z2, etc. Then just click on these menu cells to enable the pull down menu arrow then click on the arrow and select the number of gear teeth for this position. After it is selected you will see the TPI value at Cell F24 and the metric value at W24. (The possible gear values are directly below the pull down menu cell and these can be altered by just typing in these value cells)

The Feed and Cross feed values may not be accurate as I simply took one set of values from the manual and used it as the gear ratio. The manuals are commonly inaccurate or even have errors. So I just used the feed 0.005 and cross feed 0.015 rates and gear set up of the first row of the table associated with the manuals figure 3-18. These provided the draft gear ratios for all cases. So if they are in error then everything will be off by this amount and well will have to work on getting a more accurate value. Also, I have found you cannot always use the parts drawings at the ends of the manual to determine gear ratios as they are not always accurate.

@Weldingrod1 is correct about the banjos. This is what I was referring to as being "nonphysical" when the gears do not fit or do not reach the next set of gears. One can only figure this out if he has access to the lathe. Once, it is figure out then the gears at each position can be limited to the possible physical size.

By the way, people want exact TPI values, but the metric conversion on the 1130V is not exact nor does the conversion to metric from Imperial result in the standard table metric values. So we have to live with small approximations errors. This is why I wrote a macro to allow one to set an error limit during searches for Imperial or Metric thread searches.

Let me know. If it is working correctly we will get you the table you need pretty easily.

Dave L.

PS. I was a little confused by your gear box comments or ratios of 1:2:3. Maybe I miss understood which lathe model you were talking about. It appears from the 1130V manual that this A, B, C knob produced 2x ratios of TPI. Figure 3-22 shows TPI values of 8, 16, 32 (B, A, C positions, respectively). These are factors of 2x each.

PS. I am interested in your springs. Sometimes I need springs I do not have and so would be interested in making them. Tell us a bit more. Where do you get your spring wire? If you want a spring of diameter X what rod/form diameter do you need to to wind it on to get X as a final diameter. Maybe you have a reference on how this is figured out? Do you hang a weight on the wire while winding to keep it tight? What are the tricks?

 

[JPMachine]

Hi @JPMachine

Ok, so I went down this rabbit hole .... and I made a pass at building a spread sheet for the PM1130V. It is attached, but without any of the macros as posting at HM with macros is not allowed unless you zip the file and hide them. So it is of limited value as choosing values is rather tedious. Never the less, the results will confirm anything you are guessing about. However, you can use the pull down menus to select different gear values for the different positions to generate the TPI (Imperial or metric) values. If you come back to me and tell me if you think the spread sheet is working for your lathe and I can put the sheet into the workbook with the macros and post it so that we can generate a full table of all possible thread values.

Included is the ReadMe sheet to provide a bit of description of the spread sheet layout.
See Cells at Row 30, Columns M-V. I left these set up to generate the 32 TPI value. So before you change the gear settings compare the columns of gears to the manual so that you will know which columns correspond the manuals notation of Z1, Z2, etc. Then just click on these menu cells to enable the pull down menu arrow then click on the arrow and select the number of gear teeth for this position. After it is selected you will see the TPI value at Cell F24 and the metric value at W24. (The possible gear values are directly below the pull down menu cell and these can be altered by just typing in these value cells)

The Feed and Cross feed values may not be accurate as I simply took one set of values from the manual and used it as the gear ratio. The manuals are commonly inaccurate or even have errors. So I just used the feed 0.005 and cross feed 0.015 rates and gear set up of the first row of the table associated with the manuals figure 3-18. These provided the draft gear ratios for all cases. So if they are in error then everything will be off by this amount and well will have to work on getting a more accurate value. Also, I have found you cannot always use the parts drawings at the ends of the manual to determine gear ratios as they are not always accurate.

@Weldingrod1 is correct about the banjos. This is what I was referring to as being "nonphysical" when the gears do not fit or do not reach the next set of gears. One can only figure this out if he has access to the lathe. Once, it is figure out then the gears at each position can be limited to the possible physical size.

By the way, people want exact TPI values, but the metric conversion on the 1130V is not exact nor does the conversion to metric from Imperial result in the standard table metric values. So we have to live with small approximations errors. This is why I wrote a macro to allow one to set an error limit during searches for Imperial or Metric thread searches.

Let me know. If it is working correctly we will get you the table you need pretty easily.

Dave L.

PS. I was a little confused by your gear box comments or ratios of 1:2:3. Maybe I miss understood which lathe model you were talking about. It appears from the 1130V manual that this A, B, C knob produced 2x ratios of TPI. Figure 3-22 shows TPI values of 8, 16, 32 (B, A, C positions, respectively). These are factors of 2x each.

PS. I am interested in your springs. Sometimes I need springs I do not have and so would be interested in making them. Tell us a bit more. Where do you get your spring wire? If you want a spring of diameter X what rod/form diameter do you need to to wind it on to get X as a final diameter. Maybe you have a reference on how this is figured out? Do you hang a weight on the wire while winding to keep it tight? What are the tricks?

Wow Thanks for the hard work so far!! My 1130V is still at around mid-late September arrival, so I will need to confirm fitment then. For the ratios, sorry if it were misunderstood, I am not a machinist by trade! 8*1=8 (Speed B), 8*2=16 (Speed A), 8*3=32 (Speed C), I think were meaning the same thing but saying it differently.

For the springs, I am very new to it as well! I found my mandrel diameter by trial and error, it sprung out a lot more than anticipated! I started with a 3/8" mandrel 0.041" music wire, and was aiming for a 5/8" OD...It ended up being nearly 3/4" OD!

I am told there is an entire section in spring winding in the Machinists Handbook, but my bank accounts are drained from this lathe purchase and I havent bought it yet. There should be a formula to calculate springback, heat treat temps etc. Speaking of that, If you dont heat treat and you cycle the spring close to 100% compression, your resting length will get shorter and shorter... I heat treat on my gas grill at 475F for 30 mins and cool down slowly over 2 hours. Its not scientific at all, but hey it works. After over 100 full compression cycles, my spring has settled in about 1/8" shorter than it started. Again, im sure there are formulas in the handbook for this too!

To wind it, i uncoil a section of wire and run it through the hole in the guide on the carriage, then through the hole in the mandrel, wind 3 turns or so by hand, then engage the halfnut. Then let the lathe wind the rest of the screw just short of final length, then disengage the halfnut and wind 3 more manually. Finally cut the remaining wire and see if it springs to the desired OD or just blows up entirely and gets scrapped! LOL

 

[B2]

The next time I have a need, I will have to try spring winding. I have never studied spring making, but I wonder if there is not some other tricks, like winding a soft metal which hardens somewhat upon heat treatment. More like a tool steel.

I recently was in a music store where they do work on steel guitars. They had a whole barrel full of used/broken guitar strings (wires) which were waste. I sometimes need a fine stiff wire for running through a narrow hole so I ask if I could have some of the waste and was rewarded with a hole handful of wires/strings of various sizes. I had never really looked at these things before, but it was interesting. The high pitched strings were simply very stiff narrow wires of various diameters. But mid frequency/sized strings were a center steel wire with a second wire wrapped tightly around it (like a spring winding), but it was tight. So I am not for sure how it was put on the inner wire so tightly. The heavy base wires had a center narrow wire, a second wire wrapped around it like the mid frequency wire, but then a third wire wrapped around the other two. When I tried to unwrap a wound wire I found it to be very stiff and hard like a spring material! Anyway the two outer windings were both tight on the material inside the winding! So I went to wiki and u-tube to see how they are made. It turns out that the center wire is sometimes steel or even nylon and probably other materials. Likewise, the wound materials can vary. Sometimes it is steel, sometime bronze, phosphor-bronze (a nice spring material that conducts and is sometimes used for electrical contacts), even plated copper. It seems I collected strings with steel inner wire which were wound with other steels. One of the u-tube videos even said that the inner steel wire is sometimes hexagonal cross-section shaped to get the wound wire to grab the inner core wire..... so I will have to look at mine under a microscope to see. Anyway, from a free broken guitar string and learned a lot!

By the way, drilled a bunch of small holes in a PVC pipe cap and fastened the short pvc pipe to the wall to hold the strings. Before that they were all over my work bench!


WRT to speeds, I think the manual says the PM1130V has a variable speed via VFD with two possible ranges (pulley/belt change), "Spindle speed ranges: 75 to 500 & 300 to 2000 rpm".

However, the A, B, C refers to the gear ratios driving the lead screw to move the saddle/apron. For example, the first entry of the table on page 16 shows :

B = 8TPI, A=16TPI, and C=32TPI. 8x1=8, 8x2=16, and 8x4=32. This implies that the gears associated with knob A-B-C yield 2 factors of 2x. (There is no 3x factor. ) So these rates mean that when the knob is set to C the rotation rate of the lead screw is 1/4 of what it is when the knob is set to B. Likewise, when set to A the rotation rate of the lead screw is 1/2 of what it is when the knob is set to B. So the saddle travels the fastest when the knob is set to B and the slowest when the knob is set to C.

Let me know when you get your lathe and if you agree with the spread sheet calculations. Or if you like, using my workbook and macros, I can generate a table of all the possible TPI values and post that as pdf file. Maybe someone else has a PM1130V and would like to test the spread sheet posted above?

Dave L.

 

[JPMachine]

Ah yes, story of my life, terrible at math! I can figure a lot of things out but knowing multiplication in my head is not one of them!

 

[B2]

Hi @JPMachine

Wow Thanks for the hard work so far!! My 1130V is still at around mid-late September arrival, so I will need to confirm fitment then.

I understand priorities. I am not trying to push you, but did you get a chance to check out the physical layout of the gears in your 1130V? I just wondered how I should change the spread sheet I provided? I would like to remove the "draft" status and put it in with the rest of my lathe spread sheets.

Dave L.