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Drilling a hole for conduit in tight space

huse0054

Well Known Member
So I need to drill a 3/4" hole in the web of one of my rear seat ribs to pass some conduit through but there is only about 3-4" of space between the next seat rib. I have tried al/ of my right angle attachments and I have a hole punch kit but it requires a 1/2" hole to pass the threaded stud through. Any ideas on how best to accomplish such a task?
 
I have solved that problem in the past using my two right angle drills.

One that has a very small head and uses threaded bits.

One that has a bigger head and a normal chuck.

Use the smaller drill with a stubby bit to drill a pilot hole (as large as possible).

Then, put short unibit in the bigger chuck and expand the hole, starting with the tip of the unibit already poking through the starter hole.
 
I jury-rigged a contraption to drill conduit holes in similar places. It uses a 9 mm socket and a step drill whose stem I filed into a hex pattern. I used duct tape around the stem to lock/jam the step drill into the socket. Then used standards socket adapter to hook up to my drill.

I did not find an easy way to do this at right angles though. I wish the tool manufactures would come up with a threaded step drill bit set.
 
Dremel extension

If you have a Dremel with a flexible extension, then a rotary burr cutter shoulld be able to rough out a hole at an angle, which can then be finished off with the punch or some sandpaper rolled around a short length of dowel.
 
I've used a Dewalt 90 degree adapter in my cordless drill with a step bit. I just did a few of these for my seat ribs. It's a little difficult to control so in general I prefer using my angle drill but I don't have a threaded chuck adapter. You can use an angle drill to get the hole started, maybe up to a #11 or whatever size you have then switch over to the step bit, go slow.
 
Drill bit extension?

If you can get the preceding hole drilled, put the extension through the hole, put the step drill onto the extension, and go slow.
 
Drill bit extension?

If you can get the preceding hole drilled, put the extension through the hole, put the step drill onto the extension, and go slow.

This is how I drilled a new set of conduit holes into a finished set of wings. Angle drill, drill extensions, and a unibit, working through access panels.
 
Right angle drill, pilot drill #30, then use piloted countersink to enlarge hole to 3/8 or 1/2” (depending on c/s body size)
Use your hole punch.
 
Ok... awesome tips everyone and thanks much!

Here is what I did with great success.
- Right angle drill using a stuby threaded bit to get a small hole started.
-Then used a flexible drill extension with a 1/4" shank unibit attached.
-Then used a hole punch to get a nice clean 1" hole.
 
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