Will a "roll pin" work as an alignment pin. ???

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dobro1956
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Will a "roll pin" work as an alignment pin. ???

Post by dobro1956 » Sun Apr 07, 2019 9:08 pm

I have been restoring a KR Wilson pan jig for the last month. I am basically finished with the restoration. I have it as close to original specs as I can get it with my tooling. Now I plan on straightening the pan for the speedster project and then take the pan to another "known to be good" pan jig to compare my finished product to the "known" jig. If all is OK, then all I have left to do, to finish out my pan jig is to install the alignment pins. The original pins are dowel pins. They are to hold the alignment and also to allow the part to be repositioned perfectly if for some reasons the bolts work loose. I was planning on using "taper pins". But I do not have the right size "taper reamer" to do the job with. Taper reamers are not cheap. If I was to use dowel pins I would also need to buy a proper reamer, because the holes should be "reamed" and not just drilled. So after all the above typing, I am wondering if a "roll pin" will also do the job. They will work in a "drilled hole" with no reaming needed. The main thing it needs to do is to perfectly reposition the parts if they work loose or need to be removed. I think a roll pin will work for this application but I thought I would check out others opinions first. ....

Here are a couple pictures of the "know to be good" pan jig I will use to compare mine too. They show the small "dowel pins" I am referring to ...
zzzzzzzzz (1).JPG
zzzzzzzzz (2).JPG


Original Smith
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Re: Will a "roll pin" work as an alignment pin. ???

Post by Original Smith » Sun Apr 07, 2019 9:21 pm

I would not do that. Keep it original. I hope you can find the attachments, which are difficult to obtain.


otrcman
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Re: Will a "roll pin" work as an alignment pin. ???

Post by otrcman » Sun Apr 07, 2019 10:45 pm

Donny,

You have nothing to lose by trying the roll pins. They're pretty cheap. If they don't work out for any reason, pull them out and go to plan B.

My only concern is that the roll pins may not be able to withstand the wacks that the pan will require. I've never straightened a pan myself, but understand that you sometimes have to be pretty aggressive with it.

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dobro1956
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Re: Will a "roll pin" work as an alignment pin. ???

Post by dobro1956 » Sun Apr 07, 2019 11:40 pm

The two fixtures I am wanting to roll pin in place are just "test" fixtures and do not receive any abuse during pan straightening. They are just for accepting the T shaped test pins or the sliding cone as you proceed with the pan straightening. I do not believe they were ever meant to insert and leave in place as a person is beating the pan back into shape. I have done some research on the practical machinest website about roll pins vs dowel or taper pins. The concensus is for very heavy load bearing . a taper or straight dowel is probably best. But the "sheer" strength is about the same with all three types, depending on material type. The all can "sheer". It seems like roll pins came about as a quicker, easier, and cheaper way to do the same thing as dowels or taper pins. I really believe that a roll pin is more than adequate for this application, since the fixtures basically just sit there, and do nothing, till test time. I still appreciate all the input, because even though I think I may be right, sometimes Im "wrong" and sometimes "very wrong"

Original Smith. I try to keep everything original when I can. (within reason and budget). This pan jig was very abused before I got it. It had broken places, had been used as a weld table for years, and all the fixtures were missing. The threaded holes all had to be fixed with thread inserts. I believe they had used the holes for a place to drive out pins and other things for many, many, years. Langs had the rough castings for the fixtures, and after many hours of "quality time" with the lathe, I now have new fixtures.


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Re: Will a "roll pin" work as an alignment pin. ???

Post by D Stroud » Mon Apr 08, 2019 5:56 am

Donny, you may already know this, but some sizes of roll pins will accept a smaller roll pin after it has been installed, making it much stronger, not all of them will do that. Just throwing it out there. Good luck! Dave
1925 mostly original coupe.


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Re: Will a "roll pin" work as an alignment pin. ???

Post by Farmer J » Mon Apr 08, 2019 7:46 am

A split roll pin will measure a few thousands larger than the hole it is meant to go in and will require tapping with a hammer to assemble. It will also require some force to separate. A part with a smooth roll pin could be put together and taken apart many times without any force.

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Re: Will a "roll pin" work as an alignment pin. ???

Post by Mark Nunn » Mon Apr 08, 2019 8:11 am

What size taper reamer do you need? We have a few small sizes in the shop but I don't know what those sizes are. I'll take a look if I can get over there today. I don't mind lending one if we have what you need.

Edit. I checked the shop and the only size we have is #6 taper with large end at .354". That would be for a 5/16" pin.

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dobro1956
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Re: Will a "roll pin" work as an alignment pin. ???

Post by dobro1956 » Mon Apr 08, 2019 10:08 am

Mark, I think I need a #7. the small end will need to be about 1/4 inch.

I can save a few of the holes by drilling from the bottom or inside of the jig to locate the hole. The current dowel pin holes are 1/4 inch, so a taper pin would need to be about 1/4 inch at the small end. The rest of the holes will need re-located because they are blind holes and do not go all the way thru. I believe I can still easily remove the parts even with roll pins. It would be possible to tap or drive the parts from the side needed to remove them from the pins. Dowels would be the best way to go, but they require drilling the holes thru both parts, then ream the pan jig holes to a press fit, and then ream the fixture to a sliding fit. That is probably how it was done by KR Wilson. Taper pins would be second choice, but require the proper reamer and pins. The reamer would also need to be "cut" to the proper length for the blind holes. From what I am reading roll pins seems to be the modern way. They are mostly used today because they are faster and cheaper. They also were not available back in the day. If this was some critical high stress item, solid pins probably would be needed. There is no stress on these parts. so strength of the pin is not the driving factor of the pins, but I do need to be able to re-locate the fixtures in the event I needed to remove them .. More than likely I will use the roll pins. I can always change to roll pins or taper pins later if needed.


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Re: Will a "roll pin" work as an alignment pin. ???

Post by tdumas » Mon Apr 08, 2019 7:42 pm

You might try pins made from
1/4 cold rolled steel. They might just fit.

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