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DIY Heat Shrink tool extender


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I am wondering if any has info on heat shrink tooling sizes.

Yesterday I was in a pinch and needed to get a tiny thread mill down into a deep pocket.

I found a 3/8 diameter rod, drilled and reamed a .1235 hole, used a propane torch to heat it and slipped the 1/8 shank cutter into it.

It worked out quite well, and I will try probably do it on a few other tools, but really I am looking to know the sweet spots with sizes.

If the hole is too small, no amount of heat will ever open it up enough for the endmill to fit, if it is too big it may not hold the endmill causing it to pull out or spin?

Any one do this type of thing? Recommendations on tolerances, material for the holder etc...

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You can measure an existing shrink with deltronic pins. I think the haimers are .0008 under nominal if I recall and want an h6 shank tolerance. but am not sure, it could be smaller. I can get an exact number later if you want

 

I will say they expand maybe .002 or a little more with the heat. Their Machine is calibrated for their holders

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ButButBut genuine heat shrink books all spout that their mtl is *special* high expansion mtl yada yada.

Drill rod (silver steel) is just high carbon, but because it's ground good size and straight, is ideal for this sort of thing.

For small tools (drills and taps) I used to use 10mm dia, and ream for the shanks and Loctite 603 them in. None ever came out and I've done it for 25 years.

 

Edit, actually I just thought about how long and originally it would have been Loctite 601 and it's 32 years 😭

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On 9/13/2018 at 1:17 PM, Newbeeee™ said:

 

For small tools (drills and taps) I used to use 10mm dia, and ream for the shanks and Loctite 603 them in. None ever came out and I've done it for 25 years.

So you would ream a shank size hole and simply count on the Loctite to hold? Pretty slick if you ask me...

 

 

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On 9/13/2018 at 7:31 AM, chipman said:

I am wondering if any has info on heat shrink tooling sizes.

The area of study you are looking for is 'class of fit'.

heat shrink MFG'ers generally assume tooling shanks to be held a certain class (laziness prevents looking up which class of fit, specifically), then they size their stuff to match.

 Technara has a set of tools using a proprietary (?) alloy with a big expansion coefficient that needs less heat that you standard H13 tool steel.

 

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  • 3 weeks later...

Long time ago we used to extend end mill 3 mm and glued it with the lock tight superglue

It worked good

For  heavier duty tools we used silver soldering

Once I used rough ball mill HSS 25 mm dia extended to the lenght of  350 mm !

I used to mill some tricky parts for planes and it worked.

Very strong connection.

HTH

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  • 3 weeks later...
On 10/7/2018 at 9:58 AM, Newbeeee™ said:

Yes, I've silver soldered cutters too.

250ish DegC melting point ensures everything stays straight and se-risks distortion

Because we were too cheap to send large blocks out for gundrilling:rolleyes:, we silver soldered 7/16", jobber length drills into looooooooong pieces of O-1 drill rod for use in a radial drill or boring mill. We would often drill through 48" long plates like this, drilling 24" from each end. The silver soldered joint was never a problem. How "on center" you could sharpen a drill, by hand, was the biggest issue.:lol:

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