Roll Pin Tolerances In Aluminum Vs Steel?

[schemer]

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

Yes, I agree. Also, I would have to measure the compressed size of the split pin to properly size the loose hole on the center piece of the hing where it would have clearance. Initially, I thought of using a 3/16" shoulder bolt with a 10-32 thread and that would work great, but the guy either doesn't want to pay for the more expensive bolts, or he says he does not want the head of the bolt visible. I sippoe I could cut the head off and make a screwdriver slot and still get away with it.

I agree with Greg. A dowel in would be a better choice for a hinge type design. Sent from my iPhone using Tapatalk

I agree too. Now if I go with the dowel or guide pin of 5/32 or 3/16, what is the cheapest option on getting a drill bit or a reamer to do it? Find a .001 sized guide pin and use a standard drill or end mill?
Thanks,
schemer

 

[schemer]

Well, I made two steps forward and one step backwards... I got permission to use a shoulder bolt and found a deal on some and ordered them. Then I bought some Thread Forming Taps in 8-32 as this is aluminum 6061. These are listed as H7 with the pitch diameter being on the high side by .003 to .0035 so now I am back to the drill bit size problem. So the 8-32 normally uses a #29 drill bit which is .136 diameter but this is a Form Tap H7. What size drill would you use? What thread size should I go for with 55%, 65%, 0r 75% of thread? I have choices of a .1523 or a .1484 or a #25 (.1495) but that is based off of a H6 chart. I never used Form Taps before. I am thinking a #25.
Thanks,
schemer

 

[dave enrico]

im not nearly the machinist or fabricator that most of you guys are,i believe if i where making the hinges id put a bronze bushing thru where the pin goes then id cut a groove in the pin and put a c clip on without a head on the pin
dave

 

[4GSR]

Usually a H3 or H4 class of fit is normal for most smaller threads up to about 1" in size. Are you sure you want a H7 thread fit on your part? This class of thread is usually reserved for things that get heat treated where screw holes shrink a little after heat treat. Or for larger coarse threads where you want lots of clearance for some kind of plating is applied. Just asking...

 

[coffmajt]

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

What about stripper bolts but turn the heads smooth on the lathe. Jack

 

[schemer]

im not nearly the machinist or fabricator that most of you guys are,i believe if i where making the hinges id put a bronze bushing thru where the pin goes then id cut a groove in the pin and put a c clip on without a head on the pin
dave

If it were my project it would already be done. I am dealing with a picky older guy that is driving me nuts. In the end I will spend $100 on materials and taps and reamers and lose my &ss but have pins and taps etc for a future project that will never materialize. Helping people you know or people that your wife knows is over after this project. I thought of the bushings but the hinge is too small to safely add it.

Usually a H3 or H4 class of fit is normal for most smaller threads up to about 1" in size. Are you sure you want a H7 thread fit on your part? This class of thread is usually reserved for things that get heat treated where screw holes shrink a little after heat treat. Or for larger coarse threads where you want lots of clearance for some kind of plating is applied. Just asking...

I guess I will learn how to heat treat 6061 and buy a kiln just to really lose my *ss. The taps were on sale for half price. Arrrgghhh!

What about stripper bolts but turn the heads smooth on the lathe. Jack

Already ordered some as that was my original plan and I did think of cutting off the heads and cutting a screwdriver slot in it. But with my luck he will use red loctite and break one and I will have to make a new hinge. I need to check my tap drawer and if I do not have any sharp 8-32 taps I will buy some good ones and get it done one way or another.

Thanks guys,
schemer

 

[neshkoro]

One thing to consider is the fact you are using a steel pin in aluminum hinges. Not recommended as the aluminum will begin to fall to and the hinge will become a solid mess that will never move again! Just my opinion and experience.
Bill


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[neshkoro]

It should say "gall" to the aluminum. Tiny keyboard!!!


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[schemer]

One thing to consider is the fact you are using a steel pin in aluminum hinges. Not recommended as the aluminum will begin to fall to and the hinge will become a solid mess that will never move again! Just my opinion and experience.
Bill


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It should say "gall" to the aluminum. Tiny keyboard!!!


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Well I have ordered the stuff and will proceed as planned. Maybe clearance the hole a little larger to help with the potential galling and if he keeps it lubed it should not be a problem. I have looked at some commercial aluminum hinges and they use a steel pin. I bought some longer shoulder or stripper bolts so I can remove the head and then cut a slot for a screwdriver to install them. This as opposed to just turning down the head diameter and using the existing allen wrench socket. The reason for this is that I could not find any 7/8 shoulder bolts in 3/16 diameter so it ends up needing to be custom for that reason.
schemer

 

[neshkoro]

Good luck. And that's in a good way.


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