How to fit a taper pin?

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How to fit a taper pin?

This topic has 19 replies, 10 voices, and was last updated 23 November 2018 at 18:53 by ega.

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23 November 2013 at 12:27 #6956
StirlingSingle
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@stirlingsingle
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23 November 2013 at 12:27 #136225
StirlingSingle
Participant
@stirlingsingle
Hello,

I need to drill and fit a taper pin between a piston rod and cross slide collar.

The taper pin is 1/16" x 3/4"

Do i drill 1/16" and then use a small taper pin reamer, then tap the pin in?

Any info would be great.

Many thanks,

Stirling
23 November 2013 at 13:11 #136227
JasonB
Moderator
@jasonb
Measure the small end of the pin and drill to that size, then ream the hole, keep checking the fit and stop reaming once the pin starts to show on the far side when pushed in by hand. This should mean it comes through a little way when tapped in with a brass drift.

J
23 November 2013 at 14:26 #136232
ega
Participant
@ega
It may also be good idea to find some means of identifying the small end for when you want to remove it.
23 November 2013 at 14:43 #136234
KWIL
Participant
@kwil
You do not file it flush on both sides. As Jason says above, the small end just starts to show. Remove some of the fat end if you must for appearence sakes if the pin is long.. You can always measure which is the smaller if unsure.
23 November 2013 at 20:30 #136254
Martin Cottrell
Participant
@martincottrell21329
Hi,

I hope this isn't a daft question but is there a standard taper to which all tapered pins are made requiring just one tapered reamer to size the hole or are there various different tapers each needing a corresponding reamer?

Regards, Martin.
23 November 2013 at 20:33 #136255
Phil P
Participant
@philp
From memory I think imperial are 1 in 48 taper and metric 1 in 50.

Phil
23 November 2013 at 20:36 #136257
JasonB
Moderator
@jasonb
You still need a different reamer for each nominal size of pin 1/16, 3/32, 1/8" etc but all at 1:48 or the metric equivalents at 1:50
23 November 2013 at 20:58 #136264
Martin Cottrell
Participant
@martincottrell21329
Phil/Jason,

Thanks for the quick replies. One other question, when you say "nominal size" , does this refer to the pin diameter at its centre, or is it the drill size required to make the initial hole prior to reaming?

Regards, Martin.
23 November 2013 at 21:33 #136270
Sub Mandrel
Participant
@submandrel
For the smaller pins one reamer will do a couple of sizes – mine does, anyway. I have no idea if my pins and reamer are metric or imperial, but the pins in my random 'value bag' match the holes.

Neil
23 November 2013 at 22:10 #136274
John Stevenson 1
Participant
@johnstevenson1
Going to upset the Flat Earth Society [ FES ] now but sod it, don't care. I don't do PC, H&S, ironing and paperhanging.

Doesn't matter if you get metric or imperial taper pin readers as the difference between 1 in 48 and 1 in 50 over such a short length is virtually unmeasurable and is possibly within maching tolerances on the reamers any way.

Add to this you fit these with a BFH [ Big Flipping Hammer or close equivalent ] and any difference of 1.9643885624389 microns [ approx ] is soon taken up.
23 November 2013 at 22:24 #136277
Phil P
Participant
@philp
I have just been given a set of brand new 1 in 50 taper pin reamers, they were chucking them out at work because they never use them.

Anything that needs a pin of any sort gets a "seloc" type pin now. Its a time thing, all they have to do is drill a hole and bash it in.

I agree with JS you will not detect any real problems when mixing and matching taper pins and reamers until you get up to some of the much larger sizes.

Phil
24 November 2013 at 07:58 #136288
JasonB
Moderator
@jasonb
Posted by Martin Cottrell on 23/11/2013 20:58:37:

. One other question, when you say "nominal size" , does this refer to the pin diameter at its centre, or is it the drill size required to make the initial hole prior to reaming?

The Nominal size is the size that the pin is sold and described at eg 1/16", 1/8" etc

This referes to the very largest end of the pin and infact may be a smidge larger, just measured a couple of mine as an example

1/16" x 1/2" small end 0.053" big end 0.0605" drill 1.3mm (less on your longer pin which will have a smaller point

1/8" x 1" small end 0.101" big end 0.123" drill 2.5mm

I don't see how one reamer will do more than one size though, my 1/16" reamer goes from 0.044 to 0.061 and my 1/8" 0.095 to 0.127 so no way could I ream for a 3/32 pin with them

J
24 November 2013 at 13:17 #136306
Sub Mandrel
Participant
@submandrel
Ok, I measured up. My proper taper reamer is 0.086-0.114 I can't find a 1/8" pin to check, only a 3/32" at 0.069 – 0.096 (3/16&quot.

There is some overlap so I guess I am fitting the large end of the 3/16" pin and the small end of the 1/8" pin into similar sized holes! I suspect my reamer is for 3mm pins!

Looking at the lack of precision in the pins the 1/16" ones look to be simply parted off the end of the 3/32" ones. I also have a few very tiny pins at 0.029 to 0.051. I don't seem to have a reamer for these, and the presence of a needle-like taper broach in the box (probably 1:100) suggests I have been 'forcing' these wee brass ones a bit!

Neil
21 November 2018 at 22:55 #381764
ega
Participant
@ega
Contemplating fitting a taper pin and anxious not to break the reamer, I hit upon a dodge to allow me to turn the reamer by hand:

The reamer is held in a drill chuck in the tailstock turret with the chuck shank free to rotate in its seat; the reamer can then be safely turned by hand, advancing the tailstock ram as necessary.

I would not do this repeatedly for fear of enlarging the seat and was careful to check that the shank was free of burrs that might score it.
21 November 2018 at 23:13 #381769
Marcus Bowman
Participant
@marcusbowman28936
A handy device for doing this in a more controlled, and better supported, way is to mount the chuck on a long parallel shank. Make a fitting to suit your tailstock, and drill and ream it right through to suit the shank of the chuck. That lets the chuck and shank slide while being guided. I made one for my lathe, from a blank 2MT arbor, and it gets lots of use. You could also look at the Hemingway floating reamer attachment.

Marcus
22 November 2018 at 08:49 #381788
Nick Clarke 3
Participant
@nickclarke3
Quick and dirty tap and small reamer holder – blank end arbour to fit your tailstock bored to fit the shank of an SDS drill chuck.(Nominal 10mm but may be slightly under)
22 November 2018 at 10:30 #381812
ega
Participant
@ega
Marcus Bowman:

Yes, if I did this often I would use the proper device that you describe; the point of my post was that broadly the same function can be achieved without any extra work being involved.

Nick Clarke 3:

Do you mean the kind of SDS chuck supplied for use with hammer drills? They are typically of 13mm capacity and, I would have thought, rather chunky for this delicate application.

Incidentally, my SDS chuck of this type has a splined bore rather than a shank.
23 November 2018 at 18:13 #381996
Nick Clarke 3
Participant
@nickclarke3
Posted by ega on 22/11/2018 10:30:00:

Do you mean the kind of SDS chuck supplied for use with hammer drills? They are typically of 13mm capacity and, I would have thought, rather chunky for this delicate application.

Incidentally, my SDS chuck of this type has a splined bore rather than a shank.

This is the one I bought from T***station – almost 5 minutes drive from here – I said quick. Works fine.
23 November 2018 at 18:53 #382010
ega
Participant
@ega
Nick Clarke 3:

Thanks for the photo; I see what you mean about the shank.
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