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When mounting some knife hinges with #2 screws, it occurred to me (again) that I'd like some centering punches in a variety of sizes, that are someone precise (truly concentric holes).
There has got to be a set out there that will handle #2 through maybe #10 or #12 screw holes?
I have brad point bits in 64th's. I set the one that fits the opening best in place and spin backward by hand while applying a slight downward pressure. Works well and no extra tool to buy/store ;-)
I have some transfer punches and do the same sort of thing but sometimes the countersink is so deep that it doesn't work that well because they don't have a chance to register off the walls before the point is hitting the wood.Quote:
Originally Posted by glenn bradley
If I had some tubes to use as sleeves into which I could fit drill bits or transfer punches, and the tube could register on the countersink, I think it would work better.
But that pretty much describes a self-centering punch.
I wonder if there are VIX bits that small? I think I've only seen 'em go down to #4.
Yep #4 is as small as I've seen.Quote:
Originally Posted by Chris Padilla
This seems like just the ticket for a set of tools from Lee Valley.
I'm going to try combining Glenn's idea with some tubes from things like old pens and see if I can make something that will get the job done.
Not sure if they would do what you want Phil, but i have a set of these punches which so far have been fine: http://www.harborfreight.com/28-piec...-set-3577.html They are carbon steel, not expensive and go from 3/32 (is that no. 2? - i don't speak American) to 1/2 in in 1/64ths they claim. (i haven't checked the sizes in my set which didn't come from HF but look the same - and can't remember as it's been years. Can do if it would help)
They are supposedly hardened at the tips, and people seem to use them on metal - but if so i'd want to take care and not hit them very hard. (maybe even just blue the surface and spin the point to make a mark, then pop with a centre punch?) The shanks could be fairly easily bent in the smaller sizes, and hardened carbon steel tips seem likely to either be damaged or to chip if abused on metal. I use them on wood, and haven't tried steel...
Yep, those are the transfer punches I was referring to above. But note that, if a hinge hole is countersunk in such a way that there is really no meat at the bottom, then the transfer punch's point is hitting the wood before the shaft of the punch touches the walls of the hole.Quote:
Originally Posted by ian maybury
The problem with some hinges is the hole is countersunk so much that it is almost like a thin piece of sheet metal down there, there isn't enough shoulder to align the punch.
I hope I'm making sense.
So I'm thinking I need a hollow tube (plastic, aluminum, doesn't matter) that is larger than the ID of the hinge hole. I will try pushing the drill bits or punches through the tube and see if that improves concentricity.
OK, sorry. Missed that Phil.
The key if you go DIY is probably that the end of the tube is faced off squarely, better still if it's conical - and that the bore is a good fit on the punch. If you can find a tube the right size it's possible to do a nice job of chamfering/coning the end or adjusting the diameter in a drill press with a file. (rest the file on something solid if you can to stop it being 'bounced'/creating an out of round)
Another option might be a Star-M hinge drill. I have a set which came from Dieter Schmid in Germany, the smallest (with the yellow cap) has a 2mm drill which is smaller than 3/32in: https://www.fine-tools.com/scharnierbohrer.html If you order from him it may be best go for the budget ones at the bottom as it seems they give you the same ones (but add an allen key and screwdriver bit) if you order the 'premium' version shown at the top. (i was told Star M had replaced the Japanese made variety with them)
Think I've seen them on E Bay too, and that somebody in the US does them but can't find it….
Yeah I had figured I could chuck some plastic, aluminum, or brass tubing in the press and make the end conical with a file. I guess the key is to find a size with an ID that fits either a brad point bit or a transfer punch nicely. I have used some of the self-centering punches made in China and there is so much room between the actual punch and the outside part that concentricity isn't very good.Quote:
Originally Posted by ian maybury
I wonder how Krenov did this. I'd be willing to be dollars to donuts he had a little gadget he had made for starting these tiny screws.
I have a Starrett 819 Hinge Locating Punch. Self centering, spring loaded like an automatic center punch. Works great. The small end of the tapered outer shell is about 3/16" - don't know if that will work for you. I didn't measure a #2 screw head.
Maybe the Starrett punches come in other sizes.
How about these gimlets from Lee Valley? Not quite what you're looking for but at least there is a #2 in there.
These (LHS) are not too bad, the pin is about 2.8mm dia and tapers to a point so it'd probably get in - but it's not ideal. The fit is not bad, but could be tighter (i have a set): http://www.garrettwade.com/self-cent...re/p/35K08.01/
The real problem i guess is that if the hinge is rebated, then the screw holes drilled in the wood must be very precisely centred in the holes in the hinge bracket. Anything other than perfection will look bad as it's easily seen.
The issue is perhaps that any of these punch deals are subject to several successive inaccuracies: first any slop in the punch and sleeve, second the result of any out of vertical placement of the punch, and then maybe worst of all the drill has to be accurately placed in the punch mark in the wood and started without it getting bounced off centre by a growth ring or something..
One option (if time/trouble is no object, requires a lathe - just brainstorming) might be something like a specially made drill bush. It'd require first selecting a good quality hinge so that the plates are flat and the countersinks consistent. As well as having a conical tip to register in the countersink, it'd also need a wide shoulder to rest on the surface of the hinge plate to guarantee its staying vertical while drilling. Maybe thread the drill bush with the tapered tip on the outside, screw it into a cylindrical collar to form the shoulder and allow adjustment up and down - and secure it with a locknut.
Or maybe rather than machining from scratch simplify it down to a non-serrated flanged (fine pitch thread?) nut of appropriate thread size https://www.belmetric.com/metric-nyl..._677_1002.html Make the drill bush by drilling a fully threaded allen screw or bolt down the centre in the drill size (allens are alloy steel - tough) and machining the cone on the tip. Secure again with a locknut, or maybe a nyloc would secure the bush well enough against rotation. Quickie adjustable projection and self aligning bush...
Then figure out some sort of purpose made clamp to clamp it down on to the hinge and the piece of wood everything down when drilling...
This evening I took a look at the 1/16" bit I was using to drill the pilot holes for the hinge screws and looked at my jar of pens on my bench and thought the BIC pen inside tube may be just the ticket. I disassembled the pen and cut about 3/4" off the end of the tube (I'm talking about the inside portion with the ink in it, but I didn't cut into the portion with ink).
I adjusted the bit in my drill so about 1-1/4" extended beyond the chuck (so 1-1/4" minus the 3/4" long tube resulted in drilling a pilot hole 1/2" deep). I placed the hinge leaf in position (it has to be clamped or otherwise secured so it doesn't shift), held the plastic tubing in the hole with one hand, and drilled with the other.
I tested the method three times and was very happy with the results.
These knife hinges are all about attention to detail. The entire small cabinet is all about fiddly little details, in fact. But in a way, once you figure out the sequences, I can see how it could become second nature and how building cabinets in the Krenov style could even become addictive.