tachometer for Powermatic 45

[anwalt]

Gents and Ladies,

I have a new to me vintage 1971 Powermatic 45.  Turning instructions in the present day give specific rpm suggestions.  The PM 45 does not have a tachometer.  

I converted the 3phase to variable speed with a VFD.  Is experience on the forum attaching a tach on the outside drive?  I have a left hand thread face plate that could be used?  

thx
tom

[badwhiskey]

Honestly, I wing it.  I turn at 3 speeds: 1) Slow  2) Medium, and 3) Woah.  Woah is only for pens and small spindles.

[MichaelMouse]

I have a new to me vintage 1971 Powermatic 45.  Turning instructions in the present day give specific rpm suggestions.  The PM 45 does not have a tachometer.  

I converted the 3phase to variable speed with a VFD.  Is experience on the forum attaching a tach on the outside drive?  I have a left hand thread face plate that could be used?  

I take it you do not have the Reeves drive?  

You could have saved yourself money and a dilemma by using the standard 1725 motor and the sheaves provided.  Since no one I know, and that includes some adamant fans of "variable speed"  (actually, rpm) is in the habit of varying the rpm while the tool is in touch, I would favor return to the single rpm motor.  As badwhiskey says, turn to comfort, not to numbers.  The numbers are more a function of legal departments than woodworkers.  Does Lie-Nielsen give you a recommended velocity for its planes, or Stanley for its chisels?  Wood doesn't know how fast it's being worked, it only knows edge and wedge.  Though 600 rpm may seem a bit high for a rough 12" piece, you can use you saw creatively to enhance your safety.  Did it for 10-15 years with Ol' Blue, my Delta 12/16.  Even did some outboard at larger diameters.  I doubt my current lathe, a Nova 3000, has seen above 688 in years, even on finials for ornaments.  That's because I let the edge, not the wedge, do the work.  Don't need high surface velocity to slice wood with a sharp, well-presented tool.  Do need it to try and compensate for dull tools, or especially presentation, where you're wedging and stretching the fibers until they rip and "let the chips fly."

If it feels too fast for you, it is, regardless the numbers.  Turn slow and be safer.

[FrankAtl]

Since nobody else has answered your actual question and I can't answer it as far as mounting a tach, but I do have an idea. You can program most VFD's to show RPM's on the display. This would be motor RPM's and depending on your setup may not be headstock speed but it would give you a reference which would help you figure it out. Let me know which VFD you have and I can probably help you set it up if you're interested.

[MichaelMouse]

Since nobody else has answered your actual question and I can't answer it as far as mounting a tach, but I do have an idea. You can program most VFD's to show RPM's on the display. This would be motor RPM's and depending on your setup may not be headstock speed but it would give you a reference which would help you figure it out. Let me know which VFD you have and I can probably help you set it up if you're interested.

Apologies, Frank.  Figured the real question was about turning wood, not armatures.

https://www.precision-elec.com/faq-vfd-h...on-motors/

Now you need to figure the pulley ratio, and you're done.

Or turn at a comfortable setting. knowing slower is safer.

[anwalt]

Honestly, I wing it.  I turn at 3 speeds: 1) Slow  2) Medium, and 3) Woah.  Woah is only for pens and small spindles.

Edit:  sorry, it was MichaelMouse that asked about the Reeves Drive.  If the variable drive is used, then the ratios of the various pulleys & motor rpm would only work for known positions of the Reeves, which would could be changed.  

Thanks for your help though.   I thought some electronic genius may have made a tach for an old lathe
Tom 

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to answer your question, yes, I do have a reeves drive on this lathe.  

and I get your point about turn to your comfort level.

[wgbaggs]

Just a thought, if you have means of changing speeds, and it appears you do, a handheld non contact tachometer can purchased very reasonably off of Amazon. That would give you the speed readings you desire. Ymmv. Hth

Bill

[gcrimmins]

Here's the website for man who sells parts, including tachometers, for old Shopsmiths and other machines. There's a also a link where he shows several ways they can be mounted, which may be helpful. I dealt with him back when I had a Shopsmith 10ER and would recommend him. 
http://www.mkctools.com/tachulator.htm

[FrankAtl]

Apologies, Frank.  Figured the real question was about turning wood, not armatures.

https://www.precision-elec.com/faq-vfd-h...on-motors/

Now you need to figure the pulley ratio, and you're done.

Or turn at a comfortable setting. knowing slower is safer.

I haven't worked with a lathe that has a Reeves Drive and I thought the Reeves Drive was no longer operational so he installed the VFD to use for speed control. If he just used the VFD so that he could use the three phase motor with single phase power and still use the Reeves Drive for variable speed than my suggestion would be of no use. Run the VFD at 60 HZ and vary the speed by using the mechanical means.

MM, I know you suggest turning at no more than 600 RPM max but I guess I'm not as seasoned a turner as you. Sometimes I need higher speeds (or at least in my mind I do). I know you been turning a long time and have a very good understanding of proper presentation of tool to wood so I'd love to see some videos of how you produce quality cuts at those slow speeds. Do you have any of those you could post or links to YouTube you could refer me to? I'm always interested in how other people do things and most of my mentors turn at much higher speeds than 600 RPM depending on the diameter of the work and the surface speed they desire?

Thnaks Frank

[MichaelMouse]

MM, I know you suggest turning at no more than 600 RPM max but I guess I'm not as seasoned a turner as you. Sometimes I need higher speeds (or at least in my mind I do). I know you been turning a long time and have a very good understanding of proper presentation of tool to wood so I'd love to see some videos of how you produce quality cuts at those slow speeds. Do you have any of those you could post or links to YouTube you could refer me to? I'm always interested in how other people do things and most of my mentors turn at much higher speeds than 600 RPM depending on the diameter of the work and the surface speed they desire?

Thnaks Frank

Can't post videos here, and I did have some on Photobucket, but we all know what happened there.  I'll look into YouTube, but I don't like the ID requirements of many sites.  

You can easily do what you see St Roy do, present the tool and rotate the work a few inches by hand.  Least resistance means you've got it right. As old Frank Pain wrote so long ago, the wood will teach you how it wishes to be cut.  I suggest you don't NEED high Inches Per Minute to cut wood.  Something the experiment Roy does will demonstrate.  Newton approves, since it's one half of the mass times velocity squared on that loose knot flung from the rim at you! See #4.


Few things you should do automatically.
1. Keep the toolrest as close to the work as you can so you can maintain mechanical advantage.  If you're not adjusting the toolrest every two-three minutes, you're not being as safe as you can be, even if you turn at modest rpm.
2. Rest so that the part of the tool engaging the wood is above centerline on convex surfaces, below on concave (hollowing), giving some pad to keep the tool from getting under the work and catching.  
3. Hold the tool to the rest with an overhand grip on your pivot point.  Keeps you from dinging and marking the rest, as so many confess to, and allows you to twist and swing the tool a great distance at the far end to make a delicate presentation adjustments at the work.
4. Keep your body as far away from the work as your tool and arms will allow.  Especially, stay out of the throw zone on faceplate work.  Push the tool and shavings away from your body, and release them to fall, not fly.