# Electric Motor Drive for compound



## eotrfish (Sep 17, 2019)

I make some fly reels which have a shallow (4Deg to 8Deg) taper on the flanges.  I try for a mirror finish without having to polish after the parts come off the lathe. Turning the compound by hand without leaving any tooling marks is a PITA.






I found a couple of small 27V DC gear motors in my collection of "useful someday stuff" - always good to have backup














The whole assembly is secured to the top of the compound with 4 8-32 socket head caps.

Since the motor is DC it can be reversed.  Although the motor is rated at 27VDC I've run it from 12VDC to 40VDC. All the voltage change does is change the compound feed rate.  So far 27VDC seems just right for a near mirror finish. 

The idler gear train pivots on the motor centerline to engage or disengage the gear mounted on the compound handwheel - effectively turning the compound feed on or off.


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## Johnwa (Sep 17, 2019)

Great idea and nicely done.


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## kylemp (Sep 17, 2019)

Looks pretty good - any chance you can throw a video up on YouTube using it?


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## eotrfish (Sep 17, 2019)

I gave it a try but found Google/You Tube to be a pain.  PM me with an email and I'll send you an MP4 file.


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## eotrfish (Sep 18, 2019)

Here are a couple of short clips of the gadget in action.


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## Bofobo (Sep 18, 2019)

Having power feed is pretty awesome, I recently found a hack for using a T shaped bar in a drill but my newer machine has face feed but I’ll keep the idea in case I get another mini machine. I can see many older lathes benefitting from this machine. Hardest part of having the “one day box of bits” is justifying its space but one of these projects a year is totally worth it IMHO. Great work!


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## Janger (Sep 20, 2019)

@eotrfish - is making Fly Reels a bit of a business for you? A labour of love I"m sure. Nice. Very Nice. How did you approach making the gears?


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## eotrfish (Sep 20, 2019)

Janger

I have sold a few but the market for bench made reels is quite small.  I fish many of them and/or just give them away.  Some sit in my display cabinet.

To be clear - I did not make the gears.  I purchased them from SDP-SI - https://sdp-si.com/.   I then bore/face them as needed to fit the desired assembly.

The gear train design was a bit tricky because I didn't have a variable voltage power supply on hand.  This meant that I would be stuck with a feed rate dependant on the gear ratio selected.

So these are the design steps...
- determine compound feed rate to produce near mirror finish at appropriate lathe R.P.M. - I'm turning these at 200 r.p.m.
- measure gearmotor output speed at rated input voltage 27 VDC (and a few voltages above and below rated voltage)
- pick a gear ratio that fits these criteria
- pick a gear size that will fit on the compound hand wheel
- pick a gear size of the correct ratio to fit the gearmotor
- design the housing to provide clearance between the drive gear and driven gear
- design the idler - I originally considered using change gears on the output side of the idler but found I didn't need to.

This was really just an excercise is packaging the correct components.

I don't recall the exact compound feed rate but I think that I ended up with somewhere between 0.0015" and 0.002" compound feed per revolution, which gives me the desired finish.  I can use a 40VDC supply and turn at 300RPM to save a little time roughing the taper.


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## kylemp (Sep 20, 2019)

Bofobo said:


> Having power feed is pretty awesome, I recently found a hack for using a T shaped bar in a drill but my newer machine has face feed


Unless I'm not seeing it right, this is compound feed which pretty much no machines have as far as I'm aware.. It'd make cutting angles using the compound a lot more consistent which is what I'd want to use it for. I've considered making an air attachment to do this before but this makes a lot more sense.


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## eotrfish (Sep 20, 2019)

kylemp

You're seeing this right - it is a compound feed and I could not find any lathes with this feature.  Of course my buddy who owns a machine shop just chuckled and said "that's what CNC is for".

I just did a web search and found one guy who adapted a generic mill power feed - might work for you.


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## Dabbler (Oct 13, 2019)

Some guys make an adapter for a battery operated drill to power their compound...


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## eotrfish (Oct 13, 2019)

I know - I was looking for precision along with a 16rms finish so I designed this one.


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## eotrfish (Nov 16, 2019)

Yet another video...

Finish pass on 3.4” spool face




Nearly mirror


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