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Stepside
11-16-2014, 05:25 PM
For my Gary Martin Shaper I have built the gear cutting attachment as seen in
http://www.google.com/url?sa=t&rct=j...56146854,d.aWM

Once I realized the shaper it was sized for was larger than mine, I scaled the sizes to fit. It turns the blank in what seems to be an okay manner. The problem is it produces an Arc instead of teeth. Has anybody built one of these and did it work?

Let me know your thoughts.
Thanks in advance
Pete

John Stevenson
11-16-2014, 05:30 PM
Link doesn't work for me but if it's the cable operated thingy then have you used the right diameter for the master and not scaled it ?

iMisspell
11-16-2014, 05:33 PM
Following that link leads to (no worky )...


Redirect Notice
The previous page is sending you to an invalid url.

If you do not want to visit that page, you can return to the previous page.


[edit]
Opps... im alittle slow in posting.
That link dont work for me ether :)
_

Stepside
11-16-2014, 09:56 PM
John and iMisspell
I used the link when I started this odessy almost a year ago. See the A dollar a day for a year thread. The artical in the link is from The Model Engineer September 14, 1950. Later today I "googled" Gear cutting with the shaper and found the same artical by Base Circle. It uses a piece of music wire wrapped around the "Pitch Circle Disc" to rotate the gear blank as the shaper head moves accross the gear blank.

In the morning I will try to take several pictures and place them in this thread.

Thank you for the help.

Pete

The Artful Bodger
11-16-2014, 10:16 PM
I think this is the 'source' document?
http://neme-s.org/Shaper%20Books/Michael_Moore/shaper%20gear%20cut.pdf

GadgetBuilder
11-16-2014, 10:17 PM
Is this the article you're looking for?
http://www.eurospares.com/graphics/Tools/shapers/shaper%20gear%20cut.pdf (http://www.eurospares.com/graphics/Tools/shapers/shaper%20gear%20cut.pdf)

Hopefuldave
11-17-2014, 08:21 AM
I'm planning to cut gears and it seems to me this could be adapted to the lathe using a long rack-form cutter (hob) in a collet, pitch-diameter wheel and wire rotating the blank fixed to the lathe carriage?

Stepside
11-17-2014, 09:27 AM
Both Artful and Gadget both those links show the same artical and it is the one I am working from. Hopeful the srtical talks about doing it with a lathe.

I thought I understood how it would work, but I have a glitch in my thinking. I used the instructions to size both the Pitch circle wheel and the gear blank. For a 32 tooth 16DP gear the pitch circle should be 2 inches. The pitch circle disc is 2.00 -.041=1.959 The gear blank is 32+2/16=2.125 Both blanks are within .0005, which should be close enough for the application.

The reasons for making the setup is curiosity, entertainment and to avoid having to buy a cutter for a "one off" need. If I were to get good results, I would build one for my 7inch AMMCO shaper.

I will try to add some pictures later this morning.

Thanks for the help.

Pete

TGTool
11-17-2014, 09:48 AM
I'm trying to understand what you're explaining in the first post about it producing an arc instead of teeth. I haven't checked the math but I understand the principle and it seems a perfectly good approach. So starting out, if you use no crossfeed altogether but simply feed the cutter into the work you'd establish one tooth space. Instead of the gear shape it would be just a straight sided cut reflecting the shape of the cutter. Then if you were to start the feed and move the workpiece the cutter would start shaving off small chips higher and higher off the slot and generating the shape you want. Of course in this instance it's only one side and the feed would need to be reversed, crossing center, to shave off the other side of the slot to the correct profile.

So where in this does just an arc show up instead of teeth?

Rich Carlstedt
11-17-2014, 10:18 AM
Time out fellows .
The article says the wire is .041 diameter.
Can't do that !
you must do diametrical calculations from the centerline of the wire .
So if you use .041 as a calculation, you need .082 wire

Rich

PS
I suggest you use thin flat stock, like Starrett shim stock .
It is thinner ( say .002) and just as strong. Available in rolls

CORRECTION...Monday Morning Brain error. after posting the above I read the full article
The writer did it OK- the diameter of the winding drum less wire diameter does account for wire diameter as it is a radius calculation
Sorry fellows !

I did see this about 25 years ago and of course it is a easier and cheaper variation of using wire instead of a rack.
The challenge in this method is to always cut the new teeth and keep the load of cutting against the tension of the wire
I believe that the original author used a 30 #weight to counteract any movement to load the wire.
Hats off to the OP here for taking the challenge and doing a physical build.! ( Not sure the original author-Base Circle- built his concept)
Rich

Stepside
11-17-2014, 11:19 AM
Some pictures of the device and the product.
http://i1148.photobucket.com/albums/o563/72stepside/DSC_0950.jpg
http://i1148.photobucket.com/albums/o563/72stepside/DSC_0951.jpg

I am at the "hack attack stage" so there is a need for paint and proper fasteners ect. But until it works it shall remain in its ugly condition.

Optics Curmudgeon
11-17-2014, 11:58 AM
You did a lot of work on this, but didn't copy the design closely enough. It makes a big difference if the "drive wire" is on the top (as in the original) or the bottom (as in yours). The blank turns the wrong way in yours.

Optics Curmudgeon
11-17-2014, 12:06 PM
You may also find it useful to look at the article by Bamford in the January 20, 1989 issue of Model Engineer, he found a number of issues, mostly with rigidity and chatter, as well as a pitch circle problem.

Link: http://www.eurospares.com/graphics/Tools/shapers/second%20article.pdf

Paul Alciatore
11-17-2014, 01:38 PM
Yep, wire needs to be on top, not on the bottom.

Nice little shaper.

willmac
11-17-2014, 03:37 PM
I haven't read the magazine article, but this setup reminds me of a rolling gear tester like a Goulder. If that comparison makes sense then the gear blank should be using a base circle cylinder, not a pitch circle size.

Stepside
11-17-2014, 05:21 PM
I read all the replies and switched the wire to the top. It now cuts one tooth space at a time. After I get the ratchet sorted out I will see if it really cuts a proper shaped tooth.

Thanks for all the input and advice.

Pete

Stepside
11-18-2014, 09:25 AM
Rich

I am of the same impression as to the author actuall building the set-up. If he built it, then his shaper is larger than mine. The idea of using feeler gauge instead of wire would work on a larger unit where there could be more width on the pitch circle wheel. With a moving table instead of a moving head shaper one could turn the indexer around so the pitch circle wheel had more room. The moving table would make it possible to build a setup that would not require any mounting holes in the machine itself, just holes in the table the shaper is mounted to.

My plan is to clean up the parts and use proper fasteners as well as fine tune the ratchet system, After painting and mounting everything on a stout base I will cut all the teeth on a gear and share the pictures.

The shaper has been a fun build and the gear cutter was really an extra puzzle that has kept me entertained for a bit.

I appreciate both the comments and the assistance from those who contributed.

Pete

davidwdyer
11-18-2014, 12:54 PM
It's probably just my eyes, but is the bit put in backwards?

Stepside
11-18-2014, 08:13 PM
The bit is not backwards. I had the bit ground on a tool and cutter grinder. The guy doing the job did both ends of the bit 180 degrees from each other. It does cut on the forward stroke.

boslab
11-18-2014, 08:22 PM
So loom as the shaper is going back and fore, who cares what it's cutting, I jest.
If it's cutting an arc there is some sort of arithmetic or geometric progression going on, the shape of the arc should indicate what, it guess a cycloid, but poss involute
Think it's. Back to the drawing board!, keep nagging it and you will get what you want(works for the missus)
Well done so far
Mark

Rich Carlstedt
11-18-2014, 08:30 PM
Rich

I am of the same impression as to the author actuall building the set-up. If he built it, then his shaper is larger than mine. The idea of using feeler gauge instead of wire would work on a larger unit where there could be more width on the pitch circle wheel. With a moving table instead of a moving head shaper one could turn the indexer around so the pitch circle wheel had more room. The moving table would make it possible to build a setup that would not require any mounting holes in the machine itself, just holes in the table the shaper is mounted to.

My plan is to clean up the parts and use proper fasteners as well as fine tune the ratchet system, After painting and mounting everything on a stout base I will cut all the teeth on a gear and share the pictures.

The shaper has been a fun build and the gear cutter was really an extra puzzle that has kept me entertained for a bit.

I appreciate both the comments and the assistance from those who contributed.

Pete

Thanks for the comments Pete
Yes, after I posted it ( shim stock) , I realized room may be an issue.
Nice work, and please keep us posted with Pics. You are giving me ideas in another direction

Rich

John Stevenson
11-19-2014, 05:28 AM
Often though the shaper would be a good machine to CNC, especially for this application. Gear blank in a 4th axis and stepper on the travel.
Leave the ram powered as is and use a limit or proximity switch to restrict CNC movement to when the tool is out of the cut.

Black Forest
11-19-2014, 01:32 PM
Often though the shaper would be a good machine to CNC, especially for this application. Gear blank in a 4th axis and stepper on the travel.
Leave the ram powered as is and use a limit or proximity switch to restrict CNC movement to when the tool is out of the cut.

John I have a real nice one nearly brand new. I would volunteer mine for you to experiment on. I will even pay for what it costs.

The Artful Bodger
11-19-2014, 01:41 PM
It would be a real shame to have to ship it all way to the manor house at Bligeport & Sudspumpwater, best to send it on to NZ when done!