Drilling using a pin fixture

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11 years 1 month ago #9401 by reible
reible created the topic: Drilling using a pin fixture
Warning, this is advanced woodworking and you have to understand what you are doing before attempting this sort of project. I'll try to include most of the process and the whys but I'm not promising anything if you try this at home.

This will also be done in a minimum of two posts as it is going to be long. This first post will be more on the platform portion and the second will deal with the actual fixture used.

This is related to a blade storage box I built (you may remember seeing some details of this project about 2 years ago). (I really don't recall if they appeared on this forum or not... but I think it did). Any way today I was making a few more of the \"drawers\" and snapped a few pictures of the process and now I will attempt to describe and detail the process for you.

For a general idea of what is going on check out:
www.flickr.com/photos/12199425@N02/sets/72157601718312994/

When these photos were taken the project was \"in process\". The lower tempered hardboard and the cut out plywood were not yet connected to each other. I wanted to try using rivets (like how knifes are made). To do this I decided that I needed to do a little planning to make the job easier to do and to make sure it didn't take months to do. Yea I know it has been two years but I made more drawers then I had blades, and I left some of the drawers as blanks to be sized/shaped as needed in the future.

This whole project was very compact and the room between \"drawers\" was very small. This meant that the rivets would need to be flush with or below the surface. It was also important that the alignment of the holes and the counter bore all be pretty much right on the money. It was also necessary to locate the two pieces relative to each other.

My solution was to make a simple piece that would fit on the shopsmith and provide a \"pin\" as a locating point. I would then make a fixture that used the pin to locate the hole and/or counter bore.

So let's start with the piece that mounts on the shopsmith. For this I used a scrap of 3/4” plywood and started by finding a center line to work off of. It was not critical so I simply used a pencil after pushed the plywood against the way tubes and centering the plywood by eye. Two holes are needed that are align with the miter slots. The holes need to be flat bottomed and deep enough so the heads of the 1/4\"-20 fasteners are not above the surface. The end result will be by using two sliding t-nuts you have an adjustable platform that can be locked in place. To be safe you might want to mount the platform for the next part of the project. This is where the pin is located and mounted and I will go into more detail about that later, but for now it is time to find the location for the mounting. As you know the shopsmith provides a drill press depth so if the part you are planning on drill exceeds this specification then you are plain out of luck because this system will more then likely only reduce this space because of the fixture. If you are getting close to the maximum you will have to pay very close detail to seeing if this will work for you.

At this point you need to find what you are going to use as a pin. In my case I picked something you may not have and may not want to use even if you do have it. To be safe it would be nice to have a pin that can be drilled into and replaced as needed if you happen to drill to deep... Well throwing caution to the wind I went with the inserts from the pin router. I know I'm a wild a crazy guy. What ever you pick for a pin you want to make sure that it allows you to re-center after the jig is taken off and then put back. In my case I did a couple of things I will detail. First the router pins are taller then I like. I wish they were only a 1/4” high... in fact I decided to make them that high by counter boring a hole so that the pin was only above the platform surface by 1/4”. This also means that I can use that counter bore hole and the bit that drilled it to help re-center the platform. How this works is the drill bit is mounted in the drill chuck then the platform is moved into position and located by feeding the bit into the hole (drill is not running). You can then lock the quill in the down position and that will hold the platform in place while you lock it with the sliding t-nuts.

In my case using the pin router pins I added a threaded insert so I can use any of the 1/4”, 3/8” or 1/2” pins. If you happen to have the router chuck for your shopsmith this also works for the alignment. For this you screw in the insert and mount the router chuck then using the quill feed you capture the pin with the chuck.

The counter bore also works as a place for the chips to collect when you are drilling but it will need to be cleaned out from time to time... you need to make sure the jig will sit flat and in contact with the platform and wood chips can be an issue.

I will leave you with a few pictures of the platform at:
www.flickr.com/photos/12199425@N02/sets/72157605781885502/

More to come when we start on the interesting part... the fixture.

Ed

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11 years 1 month ago #9402 by reible
reible replied the topic: Re:Drilling using a pin fixture
As a quick review of the first posting, remember that we made a platform that has a pin that can be centered to the center line of the drill press. Having done that what ever is located by the pin will be drilled concentric with that. We also know that it is repeatable and is independent of drill size or type.

Now one needs to make a jig that takes advantage of the pin as a locater. That is the next part of the process and it turns out to be easy to do. In my case I located places where I wanted to drill the holes for the rivets on one of the pieces. I took some care in the layout and marked the hole locations. Since the “drawer” is made up of a part (hardboard) that slides in the case and the top plywood part needs to be smaller to fit in and again I wanted to keep things reasonable close. It also made since to drill both parts at the same time and to have the alignment of the top piece in relation to the lower done by the jig. When we get to the photos this will be clearly shown so I will not waste to many words on this part of the description.

Photo's are at:
www.flickr.com/photos/12199425@N02/sets/72157605806130951/

The fixture again was a piece of scrap plywood. I used some trimmed off pine as stops because again that is what I had on hand. I started by attaching a length of the pine to an edge of the plywood with some small nails. From this I used a framing square to locate a side and put a strip of pine down. You need to leave some open area if you can so the wood chips and dust don't collect in an inside corner and mess up that as a location point. This would be the contact areas for the bottom hardboard piece. I used a couple more pieces of pine on top of the other pine along the side. The location of these pieces set the location of the plywood piece. I added a second piece of pine to the very original pine strips so both the hardboard and the pine were located at the same points.

With the fixture now complete to the point of being able to control the location of the two parts it was time to do some drilling. For this a small bit such as a 1/16” twist drill works well. Remove the pin from the platform and made sure the bit will not go to deep as to hit any part of the platform. Actually adjust the bit so it will drill through the drawer parts and into the fixture, you need not drill through the fixture. Drill the holes at the locations marked. If you have not done so before it is a good idea to somehow mark the drawer parts so you don't flip anything around after the drilling and if they get separated you can get them back together and aligned. What you have done at this point is to mark the hole locations on the fixture.

I have the option of using one of several pin sizes but for this project I went with a 1/4” pin so I used a 1/4” drill to enlarge the 1/16” starter holes put in above. A brad point bit does really well with this and gives a nice clean hole. After drilling the holes you can clean the edges of the holes on the bottom side where the pin will be going. What is really neat about what you just did is that you have now located the drill positions for each hole you are going to make. Even if you were a bit off in location due to not being centered 1/16” hole that will be taken care of in the following steps. Since you are drilling each hole through both parts at the same time they have to line up.... OK if you mess up putting the parts in the fixture then you can make a mess of things but don't do that!!

The fixture is ready to use so install the pin in the platform and get the drill you want to use. In my case I think it was a 5/32” hole for the body of the rivet. Make sure you are set deep enough to drill through the two parts but not so deep as to hit the pin. Take the drawer that you used to mark the jig with and reposition it on the jig. Remember what I said about maybe messing up the hole locations a bit not being a big deal?? Well, this is why, you are now going to re-drill the holes! Bingo the holes are now in alignment to the fixture as will all the rest you drill.

So say you have 6 holes in every part and 10 parts, that makes 60 holes. Now if you took the time to mark each of the holes then hand aligned them and drilled them you will probably far exceed the time it took to make this platform and jig... and the platform is reusable and if you save the jig you can make more anytime you want. As you will see in the pictures you really need to write on the jig hole sizes etc if you are saving it. I know I could not remember drill sizes two years later so it was good they were written down.

Almost done now... In my case I did the drilling of body holes for a bunch of drawers then went on to change bits to a 1/4” Forester and set depth to have the rivet head below the surface. Again the bit was centered on the hole from before because of the pin location and fixture location. After doing all the plywood pieces it was time to do the hardboard. This becomes a problem because you can not simply flip the pieces over... what you have to do is locate the upside down so to speak. In my case I simply relocated the pine pieces to the same locations on the bottom of the jig, which then became the top of the jig and everything was once again in alignment after flipping the hardboard over. This might require you do a little extra thinking but that is what needs to happen to get it right...

Comments, questions, bewilderment... do you want to see more stuff like this??? To easy?? to hard?? If I heard nothing then I will assume no one is interested in this sort of stuff and think to myself why am I wasting my time doing these posts.

Ed

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11 years 1 month ago #9405 by nuhobby
nuhobby replied the topic: Re:Drilling using a pin fixture
reible,

Looks great to me, thanks for posting! Let us know what else you end up using the pin jig for.

Chris

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11 years 1 month ago #9414 by reible
reible replied the topic: Re:Drilling using a pin fixture
Hi Chris,

I have used the pin jig for several drill operations and have in mind to make a jig for making zci for the main table. I just did one of a kind out of UHMW plastic but I have a new saw blade in the mail so I will need another zci. Not sure what material I'll be useing but I guess after almost 4 years of the 520 style inserts it is time to make it easier and faster.

Check back for a new post that will be coming with in the next couple of days on how I adapted my setup for pattern sanding.

Ed

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