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Thread: Roll pins vs taper pins
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14th February 2014, 09:44 PM #31Pink 10EE owner
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It is probably more to do with where I live and what tools I have.. Although I have found situations where manufacturers have installed them where the knocking out side is impossible to get to without much greater disassembly..
By where I live I mean if I do not have the tool on hand, it is usually either Sydney or Melbourne where the closest reasonably priced reamer may be... That for me is 5 days minimum usually 7 or more.... Unless I want to pay express post...
Or course I could buy some reamers and have on hand, but it seems there are like woodruff cutters, lots of sizes and metric and imperial do not match either, (imperial 1 in 48 taper, metric 1 in 50) and I only ever seem to come across tapered pins in the older machine tools except where there are alignment reasons like gaps in beds....... Do not seem to find them in the machinery I fix, it is all bolts or split pins..
If I had a full set of reamers I may think otherwise...Light red, the colour of choice for the discerning man.
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14th February 2014, 10:11 PM #32Cba
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> I have found situations where manufacturers have installed them where the knocking out side is impossible to get to without much greater disassembly
Taper pins used in such situations should have a tapped hole at the thicker end - to insert a screw for extraction. I was surprised even my cheap Chinese Sieg mill came with such tapered pins with threaded holes!
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15th February 2014, 07:16 AM #33SENIOR MEMBER
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Nearly everything I work on has a taper pin somewhere on it.
Like a morse taper, cleanliness is paramount when installing them. I have found over the years that ensuring a clean, burr free tapered hole gives me no grief when it is removal time.
The hole 'must' be free from little ridges and chatter marks from the reamer which then requires not much more than a gentle tap with the 'appropriate' hammer.
Maybe it's method rather than design that can cause some consternation.
I have even resorted to making my own pins and always try to err on the big end being slightly bigger of course which is standard practise.
love 'em.
Phil
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15th February 2014, 01:24 PM #34
I believe that the pin holes are purposely drilled off center so that the parts cannot be put together 180deg out and the tapers in the parts not being correct.
I have only ever had 2 taper pins i could not get out-one that was probably 100 years old and one that there was no way of getting to the back side of. If you have ever had a roll pin break you will know the mess they can make, give me taper pins anyday. I even have a few taper reamers.....
If you cannot tap them out with a decent tap don't wallop them! If the part is small enough put it in a press or even make a J shaped puller that holds on to the back of the part and presses on the small end of the pin.
Ew1915 17"x50" LeBlond heavy duty Lathe, 24" Queen city shaper, 1970's G Vernier FV.3.TO Universal Mill, 1958 Blohm HFS 6 surface grinder, 1942 Rivett 715 Lathe, 14"x40" Antrac Lathe, Startrite H225 Bandsaw, 1949 Hercus Camelback Drill press, 1947 Holbrook C10 Lathe.
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15th February 2014, 01:29 PM #35
Hi Ewan, You beat me to it.. Several of the gearbox tapered pins on the Deckel FP2LB are offset just like that, and for exactly that reason. They only go one way. The pins we have been making also have a turned flange on the end, so that you pull them out rather that hitting the small end.
We make them the same as Phil by the sounds of it.. with one end bigger than the other
Ray
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15th February 2014, 05:32 PM #36
This is the tapered pin type I was referring to in the earlier post.
IMG_0681.JPG
Ray
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15th February 2014, 06:09 PM #37Philomath in training
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Yeah. Looks like a 1:49 taper.
Michael
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15th February 2014, 06:19 PM #38
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9th May 2014, 06:15 AM #39
The roll pin on my Chinese lathe was supposed to act as a shear pin.Instead an $80 shaft that drove the rack pinion become a sacrificial element to save the 20c roll pin.
Note to Chinese lathe owners with the lead screw covers,that the carriage can bind on the cover as it acts like a big sleeve near the end of its travel. Mine has a bit of brazing rod in there now.
Grahame
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9th May 2014, 09:55 AM #40SENIOR MEMBER
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I've used hard bronze brazing rod as the shear pin for years. Works well. The original shear pin was cast steel taper pin.
Roll pins never shear cleanly. Bad thing to use.
Try oiling the outside of the spiral steel leadscrew cover and you should find it won't bind.
Mine work great. Excellent invention.
Also I use Loctite 767 lube on the leadscrew.
After 10 years use there's no discolouration in the lube, and the bronze half nuts are a good as new.
RobThe worst that can happen is you will fail.
But at least you tried.
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9th May 2014, 10:10 AM #41Mechanical Butcher
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Someone showed me a safer way to remove a roll pin: Put in a solid pin that just fits inside, clamp over the roll pin with vice-grips (or even a vice) and it won't then collapse or break. Then use a tyre lever or whatever under the vice-grip jaws to lever it out.
It's taken me a long time to appreciate that a pin punch is not a drift. After smashing several of them in vain attempts to dislodge a stubborn pin, I realised that a strong, tapered drift is a better tool to just start it moving. Then when the end of the pin is flush with the surface, use the biggest pin punch that will fit to complete removal.
Jordan