I'm ready to install a 4-7/8" gauge in my '32 style steel dash. I've cut hundreds of holes in wood with cutters, but my experience with sheet metal is not pretty. The guide bit wants to hog out and move the hole saw - plus as soon as the saw cuts through at one point it binds up and trashes the cut. I don't want to mess up my virgin dash. Your best ideas or experience is appreciated!
Use oil and go slow. Doing it without a press is a pain. I actually burned up a drill doing mine. Perhaps drilling a smaller pilot hole would help?
I have had good luck clamping a 1x4 piece of wood to the dash and using light pressure, don't try to drive it through the metal. Iv'e done this on painted dashes. good luck
Drill the pilot seperately, then chuck up a dowel or steel rod in the hole saw in place of the pilot bit. I read that somewhere, have not tried it myself, but it makes sense. If the pilot can't cut the metal, then it won't enlarge the hole.
Yeah, I was going to reccomend the wood idea as well. If you have drilled holes in wood then you know the thickness of the wood does a great job holding the pilot drill bit steady.
I know what you mean about the pilot bit hogging out the hole. Try this, Instead of using a drill bit in the arbor of the hole saw just use a piece of rod. The rod wont hog out the pilot hole, it will just act as a support. Drill the pilot hole using a different drill.
When I was ready to instail my gauges, I took my dash to a machine shop and they cut the holes perfect and it only cost me about $10-$15 a hole. They were perfect. Gator
Clamp some 1x6 behind the sheet metal. I do that every time I drill any holes in, or use a hole saw on, sheet metal.
This ^^^^is good advice. My suggestion is to first cut a piece of plywood to match the opening. Mark the guage layout. Attach plywood to the item being drilled. Drill the arbor sized pilot holes. Use the smooth arbor and the hole saw to finish drilling your big hole. When you clear the plywood romove the circle and rub some wax on the wood. Finish drilling through the sheetmetal using oil and clearing the chips with a shopvac. The plywood acting as a guide along with the smooth arbor should keep the hole tight.
Yup to all the above. Turn the saw at about 90 rpm. To keep the mess down, use beeswax for a lubricant. apply to the side of the saw while it is turning. Four 1/4" holes spaced equidistant around the circumference and just right on the edge of the hole will help prevent chatter and clear the chip without having to lift the saw. It wouldn't hurt to make the holes in the wood larger. Keep enough constant pressure to keep it cutting. This isn't a job for a hand drill as being square with the surface being cut is important. A saw that is not square to the surface and cutting all the way around will cut a out of round hole even with a rod pilot
The methods described by others will work fine. The main thing with any method is GO SLOW. An alternative method is to drill a series of 1/8 holes INSIDE your cut line about 1/16 inch. By slanting the drill back and forth you can eventually work through the webs between the holes. After you get the center piece out finish the hole to the line with a die grinder and small stone. Remember, GO SLOW.
I worked my way out to within 1/4" of my cut line with sheet metal shears. I then used a half round file attachment on my sawzall to file the rest of the way. Found the file attachment at Menards for @ $20.
Good ideas-I just drilled some gauge holes in an aluminum panel using some of the methods described. I used a pice of 1/4" hardboard-masonite, I guess-and pre drilled the holes with a hole saw in the drill press. I clamped that hardboard onto the dash panel and drilled away-the hardboard was dense enough it kept the hole saw perfectly aligned-no problems with walking or movement or the hole getting hogged out at all, as long as it's clamped down tight, it should work fine... EW
This is why I'm on here. Thanks to all, and DAMON L, welcome to the HAMB. Good first post - you'll learn more here (even though you are an engineer,ha!) than living with an old hot rodder 24/7. Here goes...
The 1/4" rod pilot for a holesaw works so good that I don't even bother with a drill style pilot for wood. I always pre-drill my pilot hole with a 1/4" bit because it is much easier to get your pilot hole spot on your punch mark without the giant holesaw in the way, the solid rod pilot will make rounder holes in all materials. Good luck. Jaysin
I bought a bunch of old Greenlee hole punches at an auction years ago. They are used by electricians to punch holed in electric panel boxes. They are a two piece punch. You drill a pilot hole that is the right size and then you take one half that has a bolt through it. Stick it through the pilot hole and turn the other half on to the bolt from the other side. All you do then is tighten it with a rachet and socket and it cuts out a perfect hole. Sometimes you can pick these up cheap at flea markets. They are pretty salty if you buy new ones.
Three years ago I needed to enlarge the gauge holes in my original '32 dash tunnel. First I marked the stainless gauge plate with a sharpie while it was bolted to the firewall so I was certain the opening was centered. Then I removed the gauge tunnel and cut heavy layout board with the hole sizes needed for the SW gauges. I glued the cardboard templates to the stainless panel and carefully used a carbide cutter in an air grinder to enlarge the holes. This method is the best I've ever done to not destroy the original panel and position the holes correctly in the dash oval. Holes saws can and will wander and cut the hole larger than needed. Original stainless panels are too valuable to take a chance of destroying.
Never seen a greenlee punch 4 7/8". the only thing I can add to the above advice is to work from the backside if possible, that way if something fucks up its where it wont be seen.
All of the previous post talk about hole saws. If you want to make the holes a specific size, without buying a bunch of holes saws, try a circle cutter. I do not have a picture. It has a pilot bit just like a hole saw, with a adjustable arm with a bit at the end of the arm. Use the wood or steel backing to keep the drill bit from wobbling. good luck
Ditto on the above. This is the way that I've done gauge holes over the years. It supports the metal (less/no distortion) as well as the pilot drill.
Yea, they might not make one that size, biggest one I have is 3 inches. Well, if you end up using a hole saw I would recommend that you use a drill press if the dash piece is out of the car. You can clamp everything down and reduce the risk that the hole saw will walk on you or the dash piece will move.
Some info here on cutting holes if it helps , http://www.jalopyjournal.com/forum/showthread.php?t=451644
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