pic: 1-inch extrusion hole guide



Neat. I was looking for something like this. Is this purchased or made?

It’s definitely something you want to make. The drill bushings are roughly $100 dollars alone.

We made something similar this past offseason.

Yeah I have been wanting to make something like this for a long time but the bushing cost is what has stopped me. Does anyone have any secret low cost drill bushing sources? I’ve only checked McMaster and eBay.

Nice job OP!

The bushings we used on this were the McMaster 8492A372’s. In total they were about $70 in bushings alone.

The guide was milled out of .625" aluminum stock.
You can see that we broke one of our drills bits while using it- now it’s a pin to hold it in place.

This is very cool. I have been talking about making something like this for years now. Same as everyone else, was concerned about the busing cost and thinking of going with tool steel that could be hardened instead of bushings.

Now I am thinking about going back to aluminum and bushings. Question is, how big do you need to go to make this a versatile tool? My fist thoughts are 3" x 6" as show below.

Also curious what size drill bushing to go with. I was thinking 1/8 to make it more versatile, but we’ll probably re-drill the holes to 3/16 most of the time for 10-32 fasteners.

Looking at my original, the bushing cost will be ~$500, so it might be better at 2" x 4" instead.

CNC router for drilling?

Or some patience to find a mill on Craigslist in a good price range?

Or an XY table for a drill press?

It certainly works, but I would rather spend more money for a vastly more useful tool.

+1 on the CNC Router.

We make our own Versaframe stuff now.

Don, do you have a jig for holding tubing?
If so, can you explain or provide pictures?

Do you machine one side and then flip the material over for the other side?

I would like to ask any others how you use your CNC router to machine tubing.

Thanks

Norman

While I am firmly in the CNC router camp on this issue. Why couldn’t a team use a Flanged Sleeve Bearing like this one from McMaster-Carr for a cheap version of this fixture?

It would have to be tested, but I would wager it would work long enough to be useful. At less than a buck each, replacing bearings occasionally wouldn’t be too traumatic.

We’ve done that. It works well. 3/16" is a useful size. We have also made drill guides using 1/4".

For people saying, “use a CNC router”, I would like to hear more about how you accurately edge-find tubing- it’s a problem I think any router team without a VFD struggles with.

We bought an electronic edge finder for $35 (without shipping) and it works wonderfully. Here is Amazon link.

Given recent news on the price of predrilled stock, I’ll add some more documentation as to this project:
We actually designed 3 hole guides - for 1" extrusion shown here, 2" extrusion, and an L-jig between pairs of 1" extrusions. I’ve uploaded the CAD for all three here:
https://grabcad.com/library/frc-extrusion-hole-guides-1
The bushing to use with all of these designs are from McMaster-Carr, found here:

The holes for the bushings have rather tight tolerances- most likely you’ll have to ream them. The hole guide itself was made in 2 setups using a CNC mill, but I think you’d be able to make it using a manual if you were clever. We pressed in the bushings using a benchtop arbor press, but a vise should work just as well.

I designed this and we machined this during winter break prior to the 2018 season. The original purpose for this was in cases where we wanted regular holes but didn’t have access to CNC: namely, either when working on a frame which has already been bolted/riveted/welded together. This happened several times during the 2018 build season and it’s been very helpful to us. An alternate use for this could be in the pits, where it’s obviously unreasonable to try to get precision through standard means and the time to set up a job “properly” is essentially nonexistent.

Feel free to PM me with any questions you may have.