Roll Pin Tolerances In Aluminum Vs Steel?

[schemer]

Hi guys,
I have a question on split or roll pin use when the part is made of 6061 aluminum. I found a chart and they show a recommended range for the hole size based on the roll pin size, but I am curious if smaller or larger is the way to go so I don't mess up the parts. This will be used on some hinges I am making for a guy for an old sports car with really light fiberglass doors. The original hinges are made of pot metal and all cracked an probably not fixable. I suggested using shoulder or stripper bolts for the pin but he does not want that because of the look of the head of the bolt. The original had 3/16" pins and for some reason he didn't want to use solid pins?? He wanted to use a 10-32 flat head screw but I told him it would be impossible to find one with a shoulder as they are usually threaded all the way to the top on short sizes. I started on the hinges and made them a little thicker etc but they have to be laid out with the hinge and mounting holes the same locations and distances apart for the doors to line up. Do you see any problems using a 5/32 or 3/16 roll pin for this? I am thinking maybe just get 4 solid pins that are 5/32 x 1-1/4 or 3/16 x 1-1/4 and just doing it like the originals. And lastly, does anybody have a large assortment of solid dowel pins that could sell me a few? Thoughts?
Thanks,
schemer

 

[Bob Korves]

Hi guys,
I have a question on split or roll pin use when the part is made of 6061 aluminum. I found a chart and they show a recommended range for the hole size based on the roll pin size, but I am curious if smaller or larger is the way to go so I don't mess up the parts. This will be used on some hinges I am making for a guy for an old sports car with really light fiberglass doors. The original hinges are made of pot metal and all cracked an probably not fixable. I suggested using shoulder or stripper bolts for the pin but he does not want that because of the look of the head of the bolt. The original had 3/16" pins and for some reason he didn't want to use solid pins?? He wanted to use a 10-32 flat head screw but I told him it would be impossible to find one with a shoulder as they are usually threaded all the way to the top on short sizes. I started on the hinges and made them a little thicker etc but they have to be laid out with the hinge and mounting holes the same locations and distances apart for the doors to line up. Do you see any problems using a 5/32 or 3/16 roll pin for this? I am thinking maybe just get 4 solid pins that are 5/32 x 1-1/4 or 3/16 x 1-1/4 and just doing it like the originals. And lastly, does anybody have a large assortment of solid dowel pins that could sell me a few? Thoughts?
Thanks,
schemer

Aluminum material should not make a major difference in the fit of a roll pin. Roll pins have a fairly large tolerance of hole sizing. Here is a good general reference:
http://www.spirol.com/library/whitepapers/Hole_Preparation.pdf

 

[schemer]

Bob, thanks for the info. I know of the Spirol pins (rolled type) but cannot use them due to the person wants the pins flush and the Spirols have some recommendations on the chamfer having to exit the ends of the holes for proper strength. But the article has good info nonetheless. I ordered some stainless pins off of fleabay so I am good to go. Went with 5/32 as I can always go larger if necessary but not so easy to go the other way.
schemer

 

[Andre]

A 1/8" roll pin fits into a 1/8" hole. Generally they are .005" or so oversize, or at least the ones I have are.

 

[David VanNorman]

You want the moveing part to have clearance and the solid part a half to a thousand tight. Use the solid pins.

 

[Bob Korves]

Bob, thanks for the info. I know of the Spirol pins (rolled type) but cannot use them due to the person wants the pins flush and the Spirols have some recommendations on the chamfer having to exit the ends of the holes for proper strength. But the article has good info nonetheless. I ordered some stainless pins off of fleabay so I am good to go. Went with 5/32 as I can always go larger if necessary but not so easy to go the other way.
schemer

I sometimes install slightly long roll pins and then file and/or grind them flush with the O.D. of the part. That might not be easy on a door hinge.

 

[schemer]

A 1/8" roll pin fits into a 1/8" hole. Generally they are .005" or so oversize, or at least the ones I have are.

Thanks for the info. I was mainly questioning the aluminum hole vs a steel hole in case the pins needed to be changed and if the pin might damage the aluminum hole.

You want the moveing part to have clearance and the solid part a half to a thousand tight. Use the solid pins.

Yeah, the originals were like that but for some reason the owner decided he does not want to go that way. I would probably have to buy a reamer too as I only have a few large ones and a couple sets of adjustable ones but I do not think they go that small.

I sometimes install slightly long roll pins and then file and/or grind them flush with the O.D. of the part. That might not be easy on a door hinge.

On the Spirols I would have to go 1-3/4 and grind 1/4 off of each end but I understand the reasoning. I might slip and hit the aluminum and that would be bad.

 

[neshkoro]

I've found that using the nominal size drill for a nominal size roll pin is just too tight in most instances. When using a split roll pin, I will measure the OD and make the hole a few thousands smaller. That way you won't have to beat the daylights out of the pin to get it in the hole. I have used that method for years without any problems. Just my opinion.

Bill

 

[f350ca]

I'd be concerned about wear on the moving part of the hinge with a roll pin. The slot or edge of the spiral depending on the type is going to cut the aluminum. A solid smooth pin as you suggested is going to cause less wear.

Greg

 

[neshkoro]

I agree with Greg. A dowel in would be a better choice for a hinge type design.


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