Visited a real hack shop, some ten years ago, the guys had purchased one of the biggest patterns of Holbrook lathes made, which had a relieving attachment fitted, The reason the guys had purchased the lathe they said was to use the attachment to cut gears, using said attachment, Common sense and good council was not prevailing, so i bid them adue, and hoped they would have every success .
As an aside they had lifted a radial drill on the forklift, with the arm up and not secured, nor machine tied to forklift, was glad when i drove away !
A number of years ago I got to tour Smith & Wesson in Springfield Ma and got to see one of these machines in operation. One of the product lines that S & W makes that you might not be aware of is formed relived milling cutters. Not standard ones that you can order from a catalogue but specials. Its not as odd as you might think, in the pre CNC days of making revolvers almost every cutter was a special. And they were formed relived and made in house. These are a fascination machine to watch run, almost silent, the spindle where the cutter being made is held turns about 1 revolution every 10 seconds or so and with the slide moving in and out. The ones at S & W were massive machines for the size of cutters they were making. These lathes weighed about 10,000 lbs and would swing about 6 inches. The form tools that were used to make the form relived cutters were wire EDM cut.
Also Levin sold drawings to make a form reliving attachment. If you have the book "practical benchwork for horoligests" by Levin there is a photo of one in there. You sent Levin $5.00 and they would send you a set of drawings to build the tool. I have done a lot of looking over the years and have never been able to find a set of these drawings. I have seen one of the tool that somebody made.
1/10 rpm? I don't think my lathe goes that slow. What speed are you supposed to run a lathe when relieving?
Slow - that is why makers offered 6:1 reduction "sub headstocks" to use with RA
Relieving is described in this old book on google:
Modern Toolmaking Methods: A Treatise Om Precision Dividing and Locating
Look on page 185.
I thought Lindsay had this book reprinted, but I don't find it on his web site.
What an interesting thread, Back to the top with you!
Following up some ideas from Mtw fdu's gear hobbing thread, up in general,
Gear Hobs and hobbing - Practical Machinist - Largest Manufacturing Technology Forum on the Web
I found a thread in another forum, by Charles Lessig, showing some modifications he has made to the "Eureka" relieving device to enable it to be used in making hobs.
Eureka style gear hob reliever video - The Home Shop Machinist & Machinist's Workshop BBS
The thread also contains links to Balzer's and Taylor's US patents for devices which many decades later inspired the "Eureaka". Unfortunately, I can't read the link to "Kinks" until I get a US proxy server. The Youtube link is definitely worth watching.
Looking through Lathes.co.uk for pictures of the speed reducing heads, Lodge and Shipley's is a plain vanilla looking box, but the old Pratt & Whitney epicyclic device at the bottom of the page, with its indexing teeth and marks looks very interesting.
My memory ain't what it once was, but I think I remember Lindsy Publications had a book on relieveing attatchments. Or at least an article on it. Don't know that they still do.
Here's what seems to be the correct book on Lindsay's website:
Lindsay: Modern Toolmaking Methods
A quick check shows that Paperbackshop-US offers it as a print-on-demand book.
JohnOder no doubt recalls that, several years ago, I nearly bought a 10,000 lb Hendey with the relieving attachment, but my ardor for solving the various logistical problems cooled when I discovered that the "Sub-Headstock" needed to use the relieving attachment was absent. However, there are still moments when I wonder if forgoing that once-in-a-lifetime opportunity was the correct thing to do. Woulda been a cool thing to own even w/o the relieving attachment.
You could have stood it up in the corner while you were waiting to get to it!
several years ago, I nearly bought a 10,000 lb Hendey with the relieving attachment
Large and Ancient Hendey
You beat me to the name of the book by about 2 minutes!
site:www.lindsaybks.com lindsey books, relieving - Google Search
I know what you mean, I've been so tempted by machines with just one bit missing, that you're sure to be falling over as soon as you pass on the machine, but with the machine home, you might never find, and the human love of your life complains bitterly about the piece of rusty junk... The eternal old iron dilema.
The late J.A. Radford, built a speed reducing head and radial relieving device for a Myford, and published pictures and a description of them in Model engineer, probably around 1971. Unfortunately he doesn't give plans. I copied out the description here:Gear Hobs and hobbing
The Radford device actually looks like a slave headstock with changewheel quadrant on the back, a power drive shaft going down the back of the lathe to the reliever cam and a worm wheel on its spindle to allow attachment of a worm and division plates to use it as a dividing head.
I'd be interested if anyone knows of some good photos or plans for the device?
I'm slightly curious to the reasons why the lathes weren't just driven via the leadscrew, even if it meant fitting a larger changewheel quadrant?
I can't remember who the makers were of a wormwheel drive taking drive from the leadscrew to a lathe's spindle for cutting long helixes. Rivett and Hendey are names which spring to mind.
Update: Pictures of Rivett worm reduction drive to spindle herePage Title
Those pages which you posted from the Hendey catalogue on the big old Hendey are excellent. Thanks for keeping them up there.
Was the "improved" reliever travelling on the taper turning attachment?
Could it cut side relief in cutters with concave ends - like the topslide type reliever?
i have a Lindsey reprint of a 1925 ( I THINK) am machinist articles ...one of the hints is a cammed releiving attachment .....they used a gear cutter as a cam on the same shaft carrying the cutter needing relief ..the xslide was freed & spring loaded...a follower rode the gear cutter ( cam)& was tied to the toolpost & turning bit ..being spring loaded it followed the cam .....if anyone is interested , i will dig it out ....when i got interested a few years back , it appeared the simplest answer , other than john stevenson's method of offsetting in the chuck for a 4 tooth cutter..( which i thot was GREAT & decided right then that 4 tooth cutters wud be quite adequate for my needs..this months village press offering has an article on HOBBING a gear ( not a worm) ..cutting the hob & then using an indexing head to hold the gear blank ...hob is cut to a rack gear pattern & fluted.... & by hobbing & indexing the correct gear number shape occurs for alll size gears.....says that only 20 positions necessary for an 80 tooth small gear....cranking 80 times not necessary ............need to look more seriously at this ....
Many thanks for your patience with that reply.
I've gone back and (?re) read the scans. It does indeed say that the "D" type reliever's eccentric mounts on the taper turning attachment, and that a "C" type reliever is necessary for cutting side and end relief.
I must have been concentrating on the pictures much more than the text first time I looked through
I had also missed reading Carla's post which described older Monarch lathes with a seperate gear box which could be used for achieving the very low speeds needed for relieving multiple tooth cutters Large and Ancient Hendey
Note that the sub-head not only reduced speed, but it was bolted to the spindle nose, so it provided a second level of reduction, relative to the leadscrew. This allowed very long lead spirals and threads. The sub-head lengthened your threading leads by 6:1.... Setting up for 1TPI gave you 1 turn in 6"!