Filing Machine Motor

[Peter Cook 6Participant @petercook6]

I am planning on building a Filing Machine from the Hemmingway kit. My lathe is not big enough to provide the power, so I will need to motorise it. If possible I would like to get some information on appropriate speeds and power requirements. If anyone has a filing machine, I would be grateful if they could let me know what speeds they typically run it at?

The video on Hemmingway  website talks about a design maximum of 700 rpm, but says half that is fine.  Other videos seem to show 100-150rpm. Are these reasonable? Are lower speeds 30-60 rpm useful? How low would you go? Is variable speed useful?

If anyone has motorised a filing machine I would also be interested in what sort of motor they recommend. Clickspring and several other videos seem to use the 90W Sherline  lathe motor and speed controller, but at £300+ it seems a bit over the top. One video shows a small (20W?) 120rpm worm geared 12v motor but that is I suspect under powered and too slow. Several others seem to have used induction motors, but then variable speed becomes more complex.

Any input to the design thinking gratefully received.

[DC31kParticipant @dc31k]

Do you not have to start with the file and assess how many strokes per minute you will require?

Then you look at how those strokes per minute are translated into revolutions per minute from the prime mover.

Is it a direct connection where once up and once down is one revolution?

Unless you tell us how the leg bone is connected to the knee bone, it is impossible to say.

[bernard towersParticipant @bernardtowers37738]

My self designed one uses a small fractional hp motor with a worm drive gearbox with an output speed of 180rpm which seems to be ok. The motor does not have the hp marked on the plate but would guess it at 120watts.

[Peter Cook 6Participant @petercook6]

Thanks for the inputs. Sorry for the lack of information, but all the filing machines I have seen are  1:1 strokes per rev of the input shaft, and the Hemmingway one is. Bernard your 180rpm is a good data point.

DC – I had not considered cutting speeds for filing, never having had the ability to move a file that fast. However doing the math, assuming cutting speeds for filing are the same as for turning and milling, the Hemmingway machine has a maximum stroke of 2.125″. Assuming cutting speeds of 100ft/min for steel and 150 ft/min for brass suggests 560 rpm for steel and 850rpm for brass – which is probably the more likely use. Both feel uncomfortably fast.

Do the same cutting speeds apply to sawing as well?

I have a possible 200w motor and controller that gives me speeds from 500-4000 rpm, so If I can get a pulley set that gives me a 10:1 reduction, that will probably be the solution.

Thanks again. Any other data points gratefully received.

[Speedy Builder5Participant @speedybuilder5]

 

Sounds like a good time to read this link ??

https://www.model-engineer.co.uk/forums/topic/how-to-control-a-12v-motor-with-arduino-easy-wiring-code-examples/

 

[DC31kParticipant @dc31k]

There are some notes on the All American Die Filer (yee haw!) here:

http://vintagemachinery.org/pubs/3061/15159.pdf

Therein 210-470 strokes per minute is mentioned.

In general, if you Google ‘die filer site:vintagemachinery.org, there is a lot of other material available.

I wonder if strokes per minute is too simplistic a measurement. If you file by hand, you do so slowly, but with long strokes (and some degree of quick return) so maybe length of cut per minute would be a better metric. Similarly with (hack) sawing: slow strokes but long in length. A filing machine might need to move faster over its short stroke ot achieve the same metal removal rate.

[DC31k]

On DC31k Said:

[…]

I wonder if strokes per minute is too simplistic a measurement. If you file by hand, you do so slowly, but with long strokes (and some degree of quick return) so maybe length of cut per minute would be a better metric. Similarly with (hack) sawing: slow strokes but long in length. A filing machine might need to move faster over its short stroke ot achieve the same metal removal rate.

Excellent point … and there may be even more to consider:

When hand-filing, we naturally ease the pressure on the back-stroke

… I don’t know enough about die-filing machines, but I suspect they do not.

MichaelG.

.

Edit: __ Peter

Would I be correct in assuming this to be the machine you are building ?

https://www.hemingwaykits.com/HK2140

 

 

[Grindstone CowboyParticipant @grindstonecowboy]

Blondihacks on YouTube built one of these, I’m fairly sure she mentions motor speeds at some point.

Rob

[John HinkleyParticipant @johnhinkley26699]

Peter Cook 6,

Some while ago, a question was posed on the “old” forum in a similar vein to your original request.  In that instance, the enquirer was asking for a different approach to the usual means of achieving the reciprocal motion of the file.

I gave the idea some thought and decided that it might be worth the mental gymnastics and CAD practice to adopt a “vertical shaper” design and came up with the following:

Naturally, it attracted a number of detractors, not on here, but on YouTube.  It wasn’t meant to be a revolutionary device (pardon the pun), just an exercise to see if I could do it.  I admit that I haven’t used it much at all, though I will say that one of its attractions for me, is that the nature of the shaper-style beam action means that, depending on the direction of rotation of the motor, the down stroke can be the slow (cutting) stroke and the return (non-cutting) thus correspondingly quicker.  Additionally, the stroke itself can be altered.

To finally get to the point, the motor which I eventually used was a 12V, worm gear reduction Chinese one fed from a variable voltage power supply.  They currently cost around £12 each on that site.  The item desorption states that:

“Voltage: DC12V
Load torque: 10KG.CM
No-load speed choice : 0.6rpm/2rpm/3rpm/10rpm/25rpm/100rpm/120rpm
Suitable for: Widely used in windows, a door opener, miniature winch and other occasions.”

Assuming that the filer will only be used on thin, possibly non-ferrous material, I consider that it would be suitable for the job.

Make of that what you will.

John

 

[Peter Cook 6Participant @petercook6]

Thanks for all the inputs, most useful. Yes Michael the Hemmingway kit you point to is the one I am planning to use. I will (at some point!) have a number of six spoke clock wheels to cross out and, knowing my skills with hand tools, was planning to buy a scroll saw. However I came across the Hemmingway kit which has a bow add on which is intended to hold saw blades. As the Hemmingway kit is the same sort of price as a cheap scroll saw, building it looked like a good option as I could use it for both the sawing and filing of the wheels.

It is also small enough for the construction to be manageable (just) on my little Taig. The scotch yoke version built by Blondihacks and Clickspring is too big to make on my lathe, the castings are far more expensive and doesn’t have the saw bow.

That led to the motor question. Blondihacks uses a 220W 1750rpm induction motor and says that the kit recommends 800 rpm for the filer. Clickspring uses a 90W  motor. The Hemmingway has a design maximum of 700 rpm, and I saw John H’s videos where he used a very small 120rpm motor. So what power and speed do I need to drive the  filer became the question.

I will probably start with the 4000rpm 200W DC motor I already have ( Which already has an Arduino controller), and for the biggest reduction I can achieve with pulleys.

Thanks again for all the help.

[Michael GilliganParticipant @michaelgilligan61133]

Difficult to estimate the power and speed requirements, given that the thing was originally designed to be [generously over-] powered by the ML7

Having noted that your primary/initial interest is sawing … I would suggest looking at the Hegner site; just to get a feel for speed and power requirements.

https://www.hegner.co.uk/hegner/catalogsearch/result/index/?p=3&q=saw

… their documentation is excellent.

MichaelG.

.

Edit: __ I have just done that, and confirmed that they use 100W or 180W mains motors … so your choice seems very appropriate to me !

[Peter Cook 6]

On Peter Cook 6 Said:

[…] and for the biggest reduction I can achieve with pulleys.

 

Poly-Vee will soon become your best friend

MichaelG.

[Author]

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