How to EDM a Spline

I wonder if this might help: http://www.hexagon.de/wn10_e.htm

Or a fully dimensioned DIN 5482 drawing.

Clearly a mere schematic with simplified circular arcs isn't enough; I don't know how to generate a true involute curve in AutoCAD. (There might be a way to generate a few accurate points on it and draw a splined polyline within manufacturing tolerances.)

Correct. I wish that Autodesk would build a lisp routine that could generate a true involute curve. I have drawn very accurate gear teeth by using a rack model and "rolling" it around the periphery of the "gear" and then connected the points, so to speak. It is a royal pain.

I do have a lisp that will generate gear teeth that "look" correct, however it always draws the image at a slight rotation angle and the profile is not 100% correct. I built some rack models and they work fairly well - again it is a royal pain to generate twenty (20) or so points.

Best Regards,

Ing. Robert Forbus

wire EDM?

are you sure this is the right solution?

for large size machining we usually temper the gear, then either machine it on a mill, or grind it with a hone

and then we re-heat and quench to simulate the original induction heat treatment

but wire cut? it may take you a week to finish?

I agree with the guest. Not only is the profile critical for gears, but surface finish as well. On top of that the thinest wire I've seen used practically is .003" which means that you will have to offset the diameter a bit and leave a little room for 'slop'. This will make it extremely difficult to finish machine and polish the teeth to final dimensions... You could cut the general profile out on the edm and then machine it. But I think it would be a mistake to think you can cut the final profile on a wire edm and then just polish it up...

If I was using this gear for a high speed application I may agree, however our application is for positioning and the speed is less than 1 RPM. We do offset for the wire; and the finish that a quality EDM produces is more than adequate for our application. I am not trying to determine how to manufacture the gear, only how to reproduce the spline by generating a .dwg (.dxf) file. The link that Tornado sent looks promising, I was just hoping I did not need to purchase more software. I have already sucessfully drawn the gear profile in AutoCad and manufactured gears, just none yet with an internal spline. I do appreciate the manufacturing advice, I can use any help offered.

Firstly there is a wide range of software products out there that can produce splines in an automated fashion other than the general Autodesk mass market models.

Secondly have you'll consider the spark gap between copper and shaft along with the wire diameter, but i imagine that this an offset built into your wire cutter.

What type of wire cutter do you have make and model

Ewatfas what do you mean by find?

Are you prepared to paid for the DWG drawings or do you think the designers get out of bed for free?

I'm dead set sure the machinists i know will not get out of bed unless you give them cash and beer

If you require we can produce them (drawings and or Splines) together with any other sizes splines that you may need

Anthony@ALNO

if your speed is less than 1 rpm and you're sure you don't need precision then why not just put the peice in question on a comparator and take a few (x,Y) coordinates to get the profile. Then count the number of teeth and factor in the diameter of the gear. boom, you're done. Then if you wish to convert to DXF file, download pointor (60 bucks or so) take your xy coordinate pairs and put them in an excel spreadsheet. copy and paste the xl spreadsheet into pointor and it will spit out a dxf file for you. Then you can upload that file to your edm machine, or whatever else you were gonna do with it...

ewatfas What are your expectations in terms of cycle life

at 1 RPM and those diameters you could have 1mm Gap between some spines surfaces

i dont think you need a DXF profile i think you need a new machinist