Gears and gear cutting by Ivan Law

[jscarmozza]

Has anyone made Ivan Law's Eureka form relieving device for making involuted gear cutters? I'm stuck on the dimensions shown in the tables for the 20 and 30 degree form cutters on pages 114 and 115 of Law's book. At first glance I thought the dimensions were inches, but I don't think they are; can someone tell me what Ins or lns means? Thanks, John.

[Russ Hanscom]

Per page 116, divide the numbers in the table by the diametrical pitch.

[jscarmozza]

Thanks Russ, I read the whole book but missed that. Have you made the device? I'm just about done with it and was looking ahead to what was involved in making the form cutter but couldn't figure out what the units were. I figured it might be some dimensionless unit, but had no idea what to do with it. My buddy's nephew needs a 30 degree cutter for a spline he's making and that was my motivation for making the Eureka.
Thanks again, I don't think I would have gotten it on my own. John

[WesHowe]

While I didn't have your answer, I did look up the book and Amazon will be sending me a copy now. Looks interesting.

[Russ Hanscom]

A Eureka is on the to-do list but it has never quite made it to the top, Guess I need a project that requires several custom gears to get it to the top.

Let us know how the spline project turns out, I do have potential need for some of them.

[wsippola]

I built one, in half size about 15 years back. It works well, but I only used it for one cutter so far. I did find that the form tool I had made was not leaving a particularly good finish when relieving the cutter blank, which resulted in a less than ideal finish on the gear being cut. So spend some time or find the materials combination that will give a good finish to the cutter. I was using O1 for the cutter blank, and had ground tungsten carbide disks for the form tool.

[jscarmozza]

Russ, I'll let you know how it turns out, I'm anxious to see the thing work myself!

Wsippola, thanks for the heads up on the cutter materials, I was planning on using O1 for both the cutter and buttons. I have the stock on hand so I'll probably use it, but I'll be especially careful with the heat treatment. I'll let you know if it was successful.

John

[Russ Hanscom]

While on the topic, a number of years abo there was an article on this in the Model Engineer's Workshop that included enough equations that one could do a simple spreadsheet to calculate the properties for a cutter for any pressure angle or cutter number.

[jscarmozza]

If this thing works, that would be useful information to have. I wonder if there is a way to get that article?

[Rich_Carlstedt]

Too bad you fellows did not make it to the NAMES show in Detroit last April
I gave a seminar on home shop gear making and had samples of various approaches
I also had a handout for resources , which I am sharing below.
not sure how it will look
Rich

NAMES Seminar- Internet Links to help make Gears April 19,2015

Good construction Locations:

Mikes Workshop- Math and chart of Button Sizes http://mikesworkshop.weebly.com/designi ... tters.html
John Stevenson’s Write-ups on building a gear cutter with chart and Button Sizes http://www.metalwebnews.com/howto/gear/gear1.html
http://bbs.homeshopmachinist.net/thread ... lute+shaft

Information Sites

Rich’s write-up and photos of forming relief on the gear cutter on the Chaski Website, in a thread called Shop Made Spur Gear Cutters posted Jan 28,2012
http://www.chaski.org/homemachinist/vie ... 5&start=24
HSM website covering cutting/shaping gears called
A Shop Made Gear Cutter 4/7/2008 http://bbs.homeshopmachinist.net/thread ... screw+nuts
http://www.gearotic.com/
http://school.mech.uwa.edu.au/~dwright/ ... shing.html

Metric Gear Info
http://www.micro-machine-shop.com/module_gear_data.pdf
Least expensive source of gear cutters/sets that I have found
http://www.ctctools.biz/

Books to own

Ivan Laws- Gears and Gear cutting -1987- ISBN-10: 0852429118
Van Keuren Precision Measuring Tools ( Gear measuring system-get any old book ! )
Model Engineer Magazine
Unwin – Making Milling Cutters - Oct 1971 ( the Supreme Granddaddy Article !)
Lammas-Gear Cutting-July to November-1991

[Rich_Carlstedt]

As you can see in the above sheet and my prior postings, I do not use a gear form relieving machine/tool.
I developed another method for relief that I believe is much simpler and very much faster
as it reduces setups and offset turning
viewtopic.php?f=4&t=91985&start=24

Rich

[jscarmozza]

Thanks Rich, lots of good information!
John