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Lathe relieving attachment


Oct 14, 2003
Kemptville Ontario, Canada
Hello all:
I have been interested in learning more about relieving attachments for some time, but have not had much success finding any literature on them.
I believe P&W, Rivett, Hendey and others made these for toolmakers lathes.
Is there anyone out there who has a manual or parts breakdown or...??
I'll gladly pay for copying and postage costs

Sudbury Ontario
I have one for one of my Rivetts..... they made two types... mine is the earlier and looks really pretty neat and is very heavy........it is one of the restoration projects waiting for me (it has been waiting for 10 years) but I do have all the parts and gears.... I may even have a copy of the gear table somewhere... if I recall it did from 2 to 30 teeth..... anyway I too would be VERY interesting in any instructions...... John do yours apply? Thanks
It was late when I read this post here. Managed to find a picture of the Holbrook one with about 4 or 5 sectional drawings.
I'll scan them and see how they come out. May not be too great as it was a wartime publication and the paper is poor........later.
[ No tables though ]

John S.
Question: I have seen some brief info about relieving attachments. Can someone describe to me exactly what they do and how they actually operate on the lathe, ncluding how they are attached! Thanks in advance.
exactly what they do
You need to switch your mind set to the days when any good sized machine shop had at least one guy back in the corner that could take a hunk of tool steel or HSS and make a cutting tool for a job basically overnight. Part of this process was equiping to make milling cutters or taps.

A relieving attachment on a lathe allowed making of properly relieved or "backed off" taps and milling cutters (counter bores and end mills too if you had the right sort of RA)

Further, if a form tool was made before hand, a "form relieved" milling cutter could be made. Gear cutter is an example. These can be sharpened by grinding on face only, preserving form or profile.

Michigan for one made dedicated relieving lathes. I have seen but one.

I looked and do not have the gear chart (it was the gear chart for Rivett's spiral milling attachment that I had)..... so if anyone has the chart for this... please let me get a copy. This is from Rivett's 1911 catalog...... basically it is a gear train that connects to a cam inside the special slide that makes the tool move in and out so many times per revolution (number of teeth on cutter you are making)..... This thing has a lot of mass.... it is very heavy and in 1911 it cost $ 85. which was more than their neat round column milling attachment...... Now for the interesting part and time for someone that knows about these to fill this information in....... notice the hand crank...... was this whole operation meant to run at such slow rpm that you would turn the spindle by hand? the examples they show appear to made with wide form tools and the tool post is chunky enough to hold these and I don't think you would run a lathe very fast taking that kind of cut anyway..... so was this operation hand cranked? also of note is Rivett's spiraling attachment uses the same hand crank set up to turn the spindle while power is running the milling head.


so was this operation hand cranked?
Indeedy - at least on this small machine. Note you are hand cranking thru a reduction gear set up.

On "regular" tool room lathes you were expected to buy a "sub headstock" with your RA that had a built in speed reducer - often six to one. This clamped to bed in front of normal headstock which it was driven by.

Johnoder, your description probably makes sense to the experienced machinists here, but because I am a brain damaged child of the sixties, I still can't picture what these things do. :confused:
Are we talking here about adding another cutter, roating perpendicular to the axis of the lathe, (like a column mill would be) that would be able to (among other things) cut the 'flutes' on a tap? Then it would be 'sync'd' with the lathes lead screw so that it might even be able to cut spiral flutes on a drill bit, like a machined deep thread?
Thanks for your help....
I still can't picture what these things do. :confused:
Did you read this from Rivett?

basically it is a gear train that connects to a cam inside the special slide that makes the tool move in and out so many times per revolution (number of teeth on cutter you are making)
An ordinary lathe turns things round. A lathe with a RA on it and working modifies this "roundness" by means of a special tool slide reciprocating so many times per revolution of the work piece - this is set up to be same as number of cutting edges or flutes. By doing this and using the proper cutting tool, you can RELIEVE a cutting tool behind the cutting edge - a necessity to have it cut freely. This is the simple version of what it does.

Complicated by also having the gearing alter the rate of reciprocation as the tool is fed along toward the chuck so as to effect a helix.

Then there are face RAs - for doing ends of end cutting tools such as end mills, shell mills and counterbores.

Thanks for the replies!!
I am working away from home for a couple of days, so I'll send a couple of PM's when I get home.

I have had a brief communication with Mr. Larry Twaits who built the rather nice relieving attachment in the link you showed. He was kind enough to send me some detailed pictures. If there is any interest I'll contact him and ask if I can share them.

John S.
I'd "love" to see the Holbrook stuff.
Also, do you still have the eureka video clip you had?? I couldn't find it last time I looked.

Here's the link:-

There was also an article in MEW No57 that described an attachment for a Myford lathe to relieve hobs.
This was done by a guy called Giles Parkes and I have seen this at shows.
To be honst it works but it really needs to go a lot slower than the Myford is capable of.
Here's a link to that article as well:-


John S.

Having trouble with the Holbrook scans because of the quality, they are the old dot type newsprint version.
Now that google has a patent search, you can search on there for relieveing attachments, and find several.

The patent for the ATW relieving attachment is very detailed. I think there are two for ATW; an earlier one by Sosa, and a latter one by Hoelscher.
Always Wanted a big Relieving Attachment

Spent some years working on, and marveling at the Welin/Asbury Rotating Stepped Screw Breech machining on large ~155mm to 8 in Artillery.

The cannon size articles must be terrifying, noisy, clanking slow turning beasts... Then you had to set up to do the same thing internally...

Requred to cut the 2(or more) different Diameters of threads

a small pic here : http://riv.co.nz/rnza/hist/ord/breech.htm

The real thing is a work of art and done pre CNC....
Heres a bit better view: