Gorton pantograph help

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Russ Hanscom
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Re: Gorton pantograph help

Post by Russ Hanscom »

I ran across a company that made new collets of most types, I needed some Kwik Switch (Universal Engineering) which is what the taper is on my Gorton. About $25 each as I recall. Look up Galaxy Collets it you are interested, they make reproduction collets for most everything.
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Harold_V
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Re: Gorton pantograph help

Post by Harold_V »

If you do your work well, it has no option but to run true. Considering you're using a lathe and not a grinder, you can expect a couple tenths variation, but that's well within a functional turnout.

Good luck with the new one. Looking forward to your report.

H
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jscarmozza
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Re: Gorton pantograph help

Post by jscarmozza »

Sorry guys, I did!'t realize there were further posts. Harold, I'm about halfway through my second try making the collet, I'll let you know how it turns out. I cheated a little, I bored the collet body to 0.248" then reamed it to the finished ID of 0.250". Russ thanks for the heads up for Galaxy collets, if this try doesn't turn out well, then I may be giving them a call. John
jscarmozza
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Re: Gorton pantograph help

Post by jscarmozza »

Finished the second collet with the bored hole. This one is more accurate in all ways except for the flats on the collar, I forgot to machine them when it was in the fixture and had to hand file them afterwards. This collet runs much truer than my first, there is still a slight vibration but it doesn't appear to be much more than that in the factory made collet. In both cases the vibration feels more like a mild electric shock, not an actual vibration and there is much less sound associated with it. A 1/4" hole maybe be the smallest that I can make because I had trouble finishing the slots in the relief holes. I was almost touching the other side of the hole with the slitting saw in order to fully cut the slot into the hole. Anyway, I have another useable collet, thanks for steering me in the right direction Harold.
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Russ Hanscom
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Re: Gorton pantograph help

Post by Russ Hanscom »

fyi,

The collets look like an Acura Flex collet by Universal Engineering.

If so, you can find them at the Universal/Delvieg site. - in the $20 range.

Or, they may be just a similar shape.

Galaxy Collets is not currently making them but they do have a bit of stock on hand. I just got some WW collets from them for $12+ each.
jscarmozza
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Re: Gorton pantograph help

Post by jscarmozza »

Russ, I contacted Galaxy earlier today. They made them in the past as a special order but have none in stock. They gave me a lead that I haven't contacted yet, but plan to tomorrow. Galaxy does have reducing sleeves that may be a way of accommodating smaller sized tools. Thanks for the new lead, I'll follow up on it.
John
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Harold_V
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Re: Gorton pantograph help

Post by Harold_V »

Reaming after boring is not all that bad, as you have established location with the boring operation. The significant difference, assuming there is one, is that reamers have a propensity to create holes that are not round (multi-sided. They also offer the chance for bell-mouth). The less than round results are usually with one more side than the reamer has flutes. That can be the source of minor runout, although I'm not suggesting it is in your circumstance. It's just one thing more to keep in mind when you're faced with a critical demand for concentricity and roundness. Boring to size may have spelled the difference.

For a task like this one, where bore size is important, a (rigid) hone can prove to be quite useful. Once the hole is bored near size, the last two or three thou are honed. That results in a very round and straight hole that should be on center.

H
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NP317
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Re: Gorton pantograph help

Post by NP317 »

I have also found that a spiral flute reamer tends to make a more round final hole than a straight flute reamer.
I have ruined some parts with straight flute reamers.
And lack of experience...
Education never ends.
RussN
jscarmozza
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Re: Gorton pantograph help

Post by jscarmozza »

The 'education never ends', you can say that again! I was reflecting on what I did and I think I screwed up on the boring bar. I didn't have a small enough bar so I ground one from a lathe tool blank, but it rubbed on the back side of the hole when I got near full depth and that may have moved the work piece slightly. I'll re-grind and try again.
John Hasler
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Re: Gorton pantograph help

Post by John Hasler »

jscarmozza wrote: Wed Nov 11, 2020 3:27 pm The 'education never ends', you can say that again! I was reflecting on what I did and I think I screwed up on the boring bar. I didn't have a small enough bar so I ground one from a lathe tool blank, but it rubbed on the back side of the hole when I got near full depth and that may have moved the work piece slightly. I'll re-grind and try again.
You might still be able to use that bar if you set it up cocked at a very slight angle so that it doesn't quite rub. Thinning a boring bar always risks deflection and chatter.
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Harold_V
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Re: Gorton pantograph help

Post by Harold_V »

John Hasler wrote: Wed Nov 11, 2020 3:46 pm Thinning a boring bar always risks deflection and chatter.
True, but ANY contact of the shank with the bore eliminates any possible chance of achieving desired results. Many a boring bar has been relief ground beyond being rigid, yet will perform in an acceptable fashion. Want an example? Think of slender boring bars for boring heads. One just has to learn to be patient, to reduce spindle speed and balance depth of cut with feed rate so the bar doesn't chatter. That leaves deflection, which is often resolved by spring passes. They work well enough in most materials, but working with mild steel can test the most experienced individual's patience.

While only once, I managed to bore a .06" diameter with success. Hand ground a boring bar from a drill shank. The material being machined was sterling silver, so the less than hard shank was adequate. Wouldn't work all that well for boring steel, but there's always drill blanks.

On that subject, I wonder how many ever consider owning drill blanks. I have more than two indexes full each of numbers, letters and fractions. Beyond the indexes, I have a large number of spares of various sizes (an Ebay purchase of long ago, for almost nothing). My shop would not function well without drill blanks.

H
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SteveM
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Re: Gorton pantograph help

Post by SteveM »

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.

Don't ask how I know.

On the other hand, drilling and reaming on a drill or mill won't have that problem.

When I got my Pratt & Whitney mill, I had only one collet - 5/8". Not a lot of tooling in 5/8".

So I made a split sleeve that was 5/8" on the outside and 1/2" on the inside.

I took a piece of stock, put a knurl on it where the end was going to be, drilled/bored the hole, turned the outside, parted, flipped and faced the other end, then slit it on the mill.
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Steve
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