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"CHEAP" reamer for mold sprue ?

D

D.D.Machine

Stainless
Joined
Dec 10, 2003
Location
poulsbo, wa, usa
I have to make some cheap proto molds and would like to not use a sprue bushing and just cut the sprue right into the hot side, I have looked all over the place for tapered reamers with like 2.5* or 1/2" per foot taper and the only i can find are sprue reamers sold by the molding suppy places and there wanting like $250+ .... there has to be a cheaper way?
 
Bridge reamer or car reamer? Two names for the same thing? These are used in structural steel to "bore" two holes that dont line up to get a bolt in the hole. What size do you need? I may have extras but can not tell you the amount of taper without finding and measuring.
These are cheap on ebay, even new. Also called construction reamer on ebay as well as bridge and car.
 
taper pin reamers are only like 1* angle and from what I have read that is not enough , It sounds like guys are having the sprue not coming loose at the nozzle and leaving a cold chunk in the sprue hole.
 
I've built countless molds using a taper pin reamer and no bushing.
Run a little more aggressive sprue puller set-up. Usually you can shorten the sprue ejector pin a bit and put a minor undercut in to pull the sprue if it sticks.
 
You can definitely get tapered end mills for less than $250 each. When I started reading this thread, I thought you needed something quite a bit larger, but if taper pin reamers are in the right size range, you should be able to find something inexpensive.

If you don't want a tapered end mill, consider a crude old-fashioned tapered hand reamer, like electricians and plumbers used to use. There are a couple of styles. One is fairly narrow, about 1/4" at tip and an included angle of maybe 5-10 degrees (this from memory and mental image, not a measurement). These are still available, and a new one will cut something deeper than sheet metal.
 
I dont bother fooling around with reamers.
Often different lengths\diameters\angles are called out.

I have a cheap manual chevalier edm, and can quick whip up an electrode for whatever I need.
Then a quick polish with split pin and sandcloth. Even lapping compound on the electrode itself works well.

I can be doing more useful things while the sinker chugs away for an hour, and I dont have to worry about hitting hard spots.
 
If you're making molds, don't you have an assortment of tapered endmills anyway? But if not, something like this will get you where you need to be for twenty bucks.

Use it like a finisher end mill, don't plunge it.

McMaster-Carr
 
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