Black metric dowel pins

[AaronH]

All,

I have seen (and used) metric dowel pins that are black. These pins have had much smaller corner breaks and lead in chamfers than the average dowel. If you've ever seen the ones I am talking about you'll know because they stand out as being quite different than most pins. They're almost square on the ends. Anyone know who makese these dowels? I see that Holo-Krome makes "Black Luster" dowels, but I'm not certain these are it. I'm using the dowel as a sort of an axle. The wheel is running on the end of the dowel. I want as much contact between the dowel and the wheel as possible, ergo the smallest corner break I can get.

Thanks,
Aaron

 

[btrueblood]

From the McMaster Carr online catalog page for dowel pins:

"To aid insertion, they are beveled or rounded on both ends (except for alloy steel pins with a diameter of 7/16" or larger, which have only one rounded end). "

Alloy steel pins may or may not be black, have never ordered them, but I could understand if they were less shiny on the ends due to oxides forming during heat treatment. Dunno if the black is a requirement for you or not.

 

[juergenwt]

Look here:

http://mdmetric.com/fastindx/uj23_30.pdf

 

[AaronH]

Juergen,

I think you've got the right idea. They probably are Form B dowels. I grabbed one from the shop to take a closer look at it. According to my calipers they measure about 5.01mm. This likely is h8 tolerance and not m6, which would rule out Form A. For whatever reason these pins always have a black finish. It makes it easy to identify them.

Thanks,
Aaron

 

[FreddyZ]

You can grind any dowel's chamfered end off to make as little chamfer as you want. Or, none at all.

 

[juergenwt]

AaronH - You need a micrometer to measure dowel pins. m6 is a + tol. h8 is a minus tol.. In case of "h" the high limit is equal to the nominal size (+0)and the tol. goes to the minus side. Look up ISO/DIN 286 to find the correct tol. for your size. The coating has nothing to do with the type or size of the pin. It is there for rust protection and to give the pins surface a coating to help keep it from "freezing" in a press fit. In other words it gives it a slick coating. 2338A has m6 tol. and 2338B has h8 tol..
If you want black coating you need to look at the manufacturers catalog offer or give them a call.