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Apr 29, 2016, 12:14 AM
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Thread OP
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Mold Locating Pins


For those that CNC their molds, what are you using for pins to properly index the half's?
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Apr 29, 2016, 07:32 AM
Barney Fife, Vigilante
tom43004's Avatar
Drill a hole in the same location (center drill, not a chisel tip) on both sides of the parting plane using the CNC. I use a 1/4" drill and then buy 1/4 diameter nylon "spacers" from home depot or Lowes.

Here is what they look like. http://www.amazon.com/Round-Spacer-N.../dp/B00DIHVI8K
Apr 29, 2016, 07:47 AM
Aurora Builder
I do the same thing as Tom but use 1/4" stainless steel dowel pins from McMaster-Carr. They offer them in various precisions for your application, and the ends are usually chamfered. Good to know there is a locally available solution though, thanks Tom
Apr 29, 2016, 02:53 PM
Registered User
I use dowel pins if it needs to be very accurate. Sometimes I just drill through and bolt it together.
Aug 30, 2017, 12:14 AM
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Kevin Matney's Avatar
I use 10-24x2.5" caps for bolts and pins at the same time.
Aug 30, 2017, 10:24 AM
Aurora Builder
NEVER use a bolt as an alignment feature!!!!!!!! They are not precise and that isn't there job!!!

I have switched to these and not looked back: https://www.mscdirect.com/product/details/09663691
Aug 30, 2017, 02:12 PM
Registered User
Those Boeing spec MSC bullet nose pins and liners are normally used on heavy duty tooling and require a press fit(they are normally only glued after a mishap),and they are relatively expensive at $ 15.52 per pin/liner set.
If they are installed in the relatively flimsy amateur tooling,things could start to warp.
I would recommend hardened steel dowel pins because they are inexpensive,relatively precise
and least likely to mush when hit by a hammer.I also like the idea of using SHCS,but they may vary in diameter/straightness.
Sep 07, 2017, 12:24 PM
Aurora Builder
Kevin, that approach works well for your glass tools.

The MSC pins are intended for use in materials with a low hardness but reasonably high stiffness. They work great in Renboard tools and will work decently in aluminum tooling and corian tooling. There are also modified version for doing what Kevin Matney did with the bolts. Steel dowel pins are fine as well and what I have in several sets of tooling.
Sep 08, 2017, 07:32 AM
Barney Fife, Vigilante
tom43004's Avatar
Nylon is hard enough for our purposes, accurate enough for our purposes, and has the added benefit of being slightly flexible if your CNC isn't as perfect as the big boys machines. Also, in the event of a stickup, you can open the mold using fair force and the pins will shear before the mold is damaged. Lots of ways of varying complexity, accuracy, and cost to get it done.
Aug 25, 2019, 07:52 PM
Registered User

www.slmfg.net for Teflon or Steel Headed or Dowell Pins for Composites


Hi All,

We manufacture custom Teflon or Steel Headed or Dowell Pins for your Aerospace composites or adhesive bond applications.

Please visit us at www.slmfg.net or write us with an inquiry at [email protected],net

By the photos we see below, we can definitely help and can do short runs for you too.

All the best!

Streamined Manufacturing
Aug 26, 2019, 01:19 AM
Registered User
Roguedog's Avatar
never mind. was late and didnt see the cnc part of the OP


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