Dressmakers pin edge finder

This topic has 14 replies, 6 voices, and was last updated 31 October 2017 at 12:22 by duncan webster 1.

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30 October 2017 at 18:16 #18724
Nige
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@nige81730
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30 October 2017 at 18:16 #324496
Nige
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@nige81730
I have seen mention, a couple of times now, about the use of a dressmakers pin and a bit of plasticene to construct a makeshift edge finder/wiggler. I cant make out how this would work and YouTube has let me down. Can somebody please explain the mechanics, how the plasticene is placed to not lose the pin when the mill or drill is fired up.
30 October 2017 at 18:22 #324497
JasonB
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@jasonb
You run the machine slowly!

Your SX2.7 will go down to about 40rpm which will be fine, infact the slower the better as you can more easily see if the pin wobbles than at high speed where it would be a blur
30 October 2017 at 18:32 #324500
Nige
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@nige81730
Where/how do you place the plasticene Jason? Do you just stick a blob as close to the centre of the chuck/collet/tool as possible ? I presume we are talking about the dressmakers pins with the round plastic end to them and which end of the pin goes in the plasticene, i'm guessing the sharp end?
30 October 2017 at 18:38 #324503
SillyOldDuffer
Moderator
@sillyoldduffer
Sorry about the picture being sideways but it shows a dressmakers pin more-or-less centred on the bottom of a milling cutter with a blob of modelling clay. If it's not more-or-less vertical and roughly centred before you start, it will fly off when you wind the speed up. Goggles.

With the cutter spinning fast (>1000rpm) , the brass rod is used to gently nudge the pin into the centre position. Get it right – and it's not difficult – and the pin's point snaps into alignment with the spindle axis. Works like balancing on a bicycle. However, if you stop the mill, the point stays aligned and you can use it, perhaps with a magnifying glass, to align the cutter axis/centre on a centre pop, line, or edge. With care you can get very close. When ready to take the cut, just pull the pin and plasticine off.

Since I took the photo, someone on the forum told me the edge of a steel rule is better than a rod. It's true.

Dave

Edit. Jason hit save before I did. Now I see he recommends 40rpm rather than my 1000rpm. For what it's worth I find the pin snaps better at high rpm but hey…

Edited By SillyOldDuffer on 30/10/2017 18:42:18
30 October 2017 at 18:40 #324504
JasonB
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@jasonb
yes just stick a lump on the end of a collet chuck or stub of metal held in one. Blunt end of the pin goes into the plasticene, point faces work.

Start the mill running and then nudge the pin until the point runs true either with your finger nail or by pushing with the end of a steel rule, the eye is a good judge of when the pin is true. You can then line it up with a scribed line or punch mark
30 October 2017 at 18:41 #324505
Nige
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@nige81730
SoD: Thank you for the picture; so it is that simple Brilliant
30 October 2017 at 18:43 #324506
Nige
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@nige81730
JasonB: Thanks for the clarification
30 October 2017 at 18:46 #324507
JasonB
Moderator
@jasonb
If you don't fancy the idea of pins flying about the workshop you can buy a wobbler set that has 3 edge finders and a pin in the set. They all have a ball on one end that fits into a socket in the knurled "chuck" and are set in the same way as the sticky pin

This is on the lathe so pic is the right way up

Edited By JasonB on 30/10/2017 18:46:31
30 October 2017 at 18:53 #324509
Nige
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@nige81730
Thanks Jason. I have drawings for an edge finder set and they are on my list of things to make when I get my new workshop I was just having problems sorting out in my mind how the pin and plasticene method would work
30 October 2017 at 19:08 #324510
alan-lloyd
Participant
@alan-lloyd
They used to be called sticky pins, when I was an apprentice.
30 October 2017 at 19:26 #324512
Watford
Participant
@watford
Using an ordinary dressmaker's pin (no glass ball) with a dob of plasticene (or blue-tac) is a very useful way of locating a centre pop below a drill or centre drill in the drill press.

Mould a small lump, about the size of a sugar cube, around the point of the drill and stick the pin in as near vertical as practically possible.

Run the drill at the speed you are going to drill, and centre the pin point with the back of a thumb nail whilst it is running. It will centre and stay positioned.

Bring the pinpoint down to the centre pop and you are spot-on. Stop drill. Remove plasticene.

Keep the 'Sticky Pin' on the side of the drill casing for next time.

Usual safety precautions please.

Mike

Edited By Watford on 30/10/2017 19:27:08
30 October 2017 at 22:51 #324552
duncan webster 1
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@duncanwebster1
Posted by JasonB on 30/10/2017 18:46:09:

If you don't fancy the idea of pins flying about the workshop you can buy a wobbler set that has 3 edge finders and a pin in the set. They all have a ball on one end that fits into a socket in the knurled "chuck" and are set in the same way as the sticky pin

This is on the lathe so pic is the right way up

Edited By JasonB on 30/10/2017 18:46:31

Trouble with these is they are very long, so you get a sore right arm winding the knee up and downn, and if you have a round column machine you probably lose alignment. I have it on te list to make a very much shorter version, watch this space.
31 October 2017 at 07:33 #324569
JasonB
Moderator
@jasonb
That is what a quill is for!
31 October 2017 at 12:22 #324621
duncan webster 1
Participant
@duncanwebster1
Only if you want to have the quill stuck right out for most of your machining.
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