Gorton pantograph help

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Harold_V
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Re: Gorton pantograph help

Post by Harold_V »

SteveM wrote: Thu Nov 19, 2020 5:04 pm Even drill and reaming might present problems.

If the tailstock and headstock aren't in perfect alignment, you can end up with a tapered bore.
There's where a rigid hone shines. Assuming there's enough material left in the bore to allow honing for size without going oversized, a rigid hone, properly applied, will straighten and round the reamed hole, generally without loss of concentricity.

In order for the slight misalignment of the tailstock to be of little consequence, the bell-mouth that is common can be eliminated by not gripping the reamer shank deeply in the drill chuck. I have a habit of gripping only the last quarter inch or so. That allows the tip of the reamer to seek center without having to overcome the rigidly held shank. If the reamer is long and the misalignment small, it will allow an on-size hole, assuming the reamer is removing a modest amount of material and fed properly.

H
Wise people talk because they have something to say. Fools talk because they have to say something.
jscarmozza
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Re: Gorton pantograph help

Post by jscarmozza »

Ha! Learned something new today and it's only 8:30 AM, I always hold my reamers as deep in the chuck as I can...and they never line up with the hole I'm trying to ream, thanks Harold.
Since my goal is to use the pantograph and not make a career out of making parts for it, I bought an array of collets from Galaxy Products. Great people to deal with and beauiful collets, but unfortunately for me, too small for my machine; my 1" length was the tapered portion, theirs was the OAL. But again I learned something! What I couldn't tell from the 3/8" ID collet I had, which is the largest diameter collet for this machine, is that for smaller IDs the bore isn't the full length of the collet but rather about 1/3 of the OAL. So back to the shop today armed with a re-ground tool and new knowledge. I'll let you know how it turns out.
Russ Hanscom
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Re: Gorton pantograph help

Post by Russ Hanscom »

Not sure what collet series you chose, but most of them are available in series of different lengths. Now that you know how they are measured, might recheck with Galaxy. For example, the FA collets are in five different series, and I have collet chucks for most.
jscarmozza
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Re: Gorton pantograph help

Post by jscarmozza »

Hi Russ, Gorton collets are not part of Galaxy's regular production line, Scott dug through old special orders and found a few left over Gorton collets from a lot he made a few years ago. Unfortunately they were the wrong size for my machine. Apparently Gorton made changes to its models during their production life, so some parts from early machines don't fit later machines. It broke my heart to send the collets back, they were beautiful. I just finished my third try at making a collet and it wasn't any better than the second try. So, I'm onto plan 'C'', which will be to look for tooling with 3/8" shanks and get on with using the pantograph.
Russ Hanscom
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Re: Gorton pantograph help

Post by Russ Hanscom »

https://www.universaldevlieg.com/ Try this site. They took over the Universal Engineering line and have most of the collets in current stock.
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NP317
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Re: Gorton pantograph help

Post by NP317 »

Just to throw in a humorous thought,
Every time I read the discussion title, I picture mounting a Gorton pantograph on an electric locomotive!
Lots of laughs.
Happy Thanksgiving to all.
RussN
John Hasler
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Re: Gorton pantograph help

Post by John Hasler »

Now you've got me visualizing that machine bolted on it's side to the top of a locomotive and being used to keep a shoe in contact with an overhead cable.
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Harold_V
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Re: Gorton pantograph help

Post by Harold_V »

You shouldn't be having issues with making a collet. If you understand the principles of roughing and finishing, you should pursue a collet in that fashion. Get it near size in all physical dimensions, then take light finishing cuts to establish sizes. To finish even one dimension before roughing the entire part is a mistake.

You're best served to not ream if you can avoid doing so, as even the best reamed hole offers at least a minimal chance of eccentricity. Bore for size, in other words. It's not all that hard, especially if you choose a respectable material from which the collet would be made. In this case I'd suggest the use of StressProof. It machines extremely well and serves well in service without heat treat. Alternately, if you don't care about longevity, you might consider any of the free machining mild steel alloys. 12L14 comes to mind.

I tried to contact you via email by the address you provided for the board, which is not a good address. Your loss. I had something I wanted to give you for your Gorton.

H
Wise people talk because they have something to say. Fools talk because they have to say something.
jscarmozza
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Re: Gorton pantograph help

Post by jscarmozza »

This is my procedure for making the collet. The finished collet is 1-3/16" OAL so I cut a piece of stock 2-1/2" long to have about an inch held in the chuck. I then face off both ends and drill a relief hole in the end held in the chuck. After that I true it up in the 4 jaw chuck and center drill for the dead center, lube the center and start cutting the external 1-1/2" per foot taper taking 0.005" cuts until I reach the proper dimensions, then I turn the straight part of the collet nose and collar to the proper dimension. All this time the work is held ibetween the chuck and dead center, now I remove the center and drill a 3/16" through hole in the collet and begin the boring operation. My first boring cut just touches the hole ID and on every other pass after that I advance the tool 0.003 until I get the proper collet ID dimension (sometimes I ream the last few thousandths) . I then mount the work in a hex 5C collet holder, drill the relief holes, cut the slots, then put it back in the lathe and part off the collet from the mounting stock. That is pretty much what I have been doing and just can't bring it over the finish line without some vibration. John
jscarmozza
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Re: Gorton pantograph help

Post by jscarmozza »

I wanted to make two 1" scale expansion links and thought this maybe a perfect project to use the pantograph. I made a three times larger 1/4" thick plywood template of the link and traced it out on the pantograph using a 3/16" four flute end mill. After three screw ups I got it and learned a few things (that should have been obvious) on the way. First don't rely on double sided tape to hold the template, it works for milling wood casting patterns, but you have to press too hard against the template when milling steel to rely on tape. Don't use carbide end mills, the pantograph isn't rigid enough for brittle carbide and you will instantly break a carbide end mill. Take light cuts, 0.010" to 0.015" per cut and use plenty ou cutting oil. What I didn't expect was that a cut along an edge of the stock vibrated a lot, while a slot cut vibrated much less. The stock was 1/4" thick hot rolled steel, I carefully cut the expansion link coupon leaving about 0.010" of metal to hold it, took it off the machine, popped it out and deburred it. I think trying to make all of these compound curves using a manual milling machine would be very tedious at best.
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jscarmozza
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Re: Gorton pantograph help

Post by jscarmozza »

I have been playing with this thing a lot, milling out small metal parts for a locomotive project and wood patterns for various casting projects. To extend its capabilities I bought a set of 1" brass copy (letters) from E-bay, but mistakenly bought mirror image letters (reverse) which did not make me happy, after recovering my composure I realized that they could be very handy for some types of pattern work. I made a trial mold and cast an engine builder's plate (photo attached) to see if an engraved metal mold could produce a clear and distinct casting. It turned out pretty good in spite of it being an open mold,i.e.surface tension issues. The letters are 1/10" and 1/12" high and 0.005" deep, I used pot metal for this pour and may continue to use it for future plates. I'm going to have to work on the method so that I get consistent castings.
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image.jpeg
jscarmozza
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Re: Gorton pantograph help

Post by jscarmozza »

A parting shot regarding pantographs, within their range you can do a lot of things with them. I make templates from 1/4" plywood and trace out all kinds of things from wood casting patterns,to small metal parts. I engraved number plates for my locomotive and a builder's plate mold that I cast the plate from. I don't have the skill level to make some of these things with conventional machines but I'm able to make very intricate pieces by tracing out a series of templates. If one becomes available near you at the right price and has collets, seriously consider it...it's like having a low tech CNC.
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Wheel pattern routed
Wheel pattern routed
Number and builder plates engraved
Number and builder plates engraved
Eccentric link parts milled
Eccentric link parts milled
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