Hi, Can anyone suggest the best tool to use to cut a hole in a metal lens board to fit a Copal 1 lens please?
Thanks Dave
Hi, Can anyone suggest the best tool to use to cut a hole in a metal lens board to fit a Copal 1 lens please?
Thanks Dave
First mark the center and protect the visible side with something like masking tape. Best would be a lathe. Next I'd use a mill with a rotary table. Otherwise the old school way: marking out with a compass, drilling holes inside (a bit from the marked out line), sawing between the holes and then with a lot of patience and a half-round file filing just to the marked line. If you have a large cone drill then drill close up to the marked line and file the last bit. You need to file as a cone bit leaves a conical hole in something a thick as a lens board.
Expert in non-working solutions.
I use a Hole-saw and a drill press. Make sure the board is clamped tightly to a backer piece of wood. Go slow, use some cutting oil (or any oil really). Aluminum is soft and will cut pretty easy. Wear gloves.
1. First I mark the hole size on the back of the lens board or on the front which has been covered with white masking tape.
2. Drill a small hole just inside of the marked circle
3. Using a small Craftsman or Dremel jig saw, I very, very slowly cut out the hole just inside of the marked circle
4. Finally mount the lens board in a vice and file out the final circular opening.
Have done this with many OEM Sinar boards. Secret is to cut out the hole with the jigsaw very, very slowly. My blades are made for cutting wood, but work fine with cutting out holes in aluminum lens boards. Have yet to have a blade break. Blade is thin Kerf for "cutting hard or soft wood and plastic 5/32"-1/2" thick". 18.5 TPI (teeth per inch). Previously drilled many holes just inside the marked circular opening and round filed the final opening. The above procedure takes way less time and really cuts down on the final filing time.
I wouldn't recommend a jigsaw, and I sold the best of the best, $700 apiece. It's hard to cut a small hole diameter accurately without a narrow blade, and narrow blades are the most likely ones to snap. Good lensboards aren't ordinary aluminum, but relatively resistant die-cast alum. alloy. But if you choose to do so, firm clamping and eye goggles. But I think Greg is using the term jigsaw differently than me, meaning a small bench device rather than a portable jigsaw. Blades can snap in that case too, so have protective eyewear, and also beware of the possibility of metal splinters to hands. I greatly prefer a fly cutter on a serious drill press, unless you have a milling machine.
A two step solution from me. Cut out the appropriate size hole in a decent quality plywood with a jig saw or saber saw. Might have to follow up with a curved file, till it's exactly the size you want. Naturally, the plywood piece needs be somewhat larger to accommodate the next step.
In the next step you'd use a router with a "follow" bit similar to this: https://www.amazon.com/Bosch-85680M-...296747&sr=8-94
Anyway, smaller bit like 1/4" or so would be better than 1/2" to keep up with the contours. Just following the walls of plywood shouldn't be difficult. To prevent the router from skating all over the place, start slow and take out small amounts of metal at a time (like 1/16" ?)....till you have a circle that you desire. Good carbide bit will chew up the alum/metal in no time.
It's a given that you have to line up the hole in plywood accurately and take usual precautions with eye protection and clamps to keep the work solidly in place.
Les
No, no, no, Les ... That's a bit for Formica, and you risk the carbide tip flying off like a bullet at router RPM speeds. I've seen it happen. Take it from someone who handled one of the largest Bosch dealerships in the country for over three decades, and by far the biggest dealer of Freud in the entire country. Bosch now owns Freud. A correct alum. bit has a different type of carbide, a negative rather than positive rake angle of carbide entry, and costs about four times as much. If it were ordinary soft alum. plate, you might get away with it; but for sake of general discussion, most official blank lensboards are diecast, and much harder. For the record, I own and use all these kinds of bits, so understand the distinction quite well.
I've always used a hole cutter
https://www.amazon.com/General-Tools...84125741&psc=1
In a drill press. Go slowly. Clamp everything firmly. Can't simply hold with your hands. Keep the cutter length as short as possible. It will make an intolerable sound as you cut. Wear ear plugs. Cut half way, then flip it over and cut the rest.
Be careful, always
There are two sizes of those General fly cutters, both adjustable per diameter. I tightly clamp the lensboard to an oversize wooden board using short wood screws with little rubber gaskets, to prevent marring the lensboard edges. Then the larger wooden board is firmly clamped to the drill press platform. Always use low RPM and cutting fluid when working with either a fly cutter or large metal-cutting holesaw.
You are right, it is a small portable bench device. Craftsman (new & still in sealed box) that I picked up at a garage sale for maybe all of $20. Actually wear a pair of CU glasses with a pair of safety glasses in front of them. Tried to use a pair of leather gloves but lost the touch/sensitivity of being able to guide the lens board very, very slowly along the circular cutting path. The front of the blade (teeth) to the back is less than 2mm, so cutting the circle doesn't cause a lot of side pressure/torque? on the blade. It can take me, guessing here, 10-15 minutes to cut the whole because I am feeding the material ever so, so slowly.
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