Altering a tool shape

Might I suggest your plugs finish at 5.08, not 5.3. Point 3 inches is quite a bit to drive into a .500 hole. You probably would have trouble starting a .510 teak plug in a .500 teak hole. You'd have to hammer it in and the wood would probably split in the wrong place.
 
I appreciate your concern, Tom, but it's misplaced here.

The problem is that the holes into which these plugs go have had multiple plugs installed and removed over the last 47 (!) years, so they're actually considerably rounded out and enlarged. I measured the diameters with calipers, and the largest was a bit over .52, so 5.08 wouldn't really do the job; fortunately, they're mostly reasonably round, despite the enlargement. I have to assume that prior pluggings did something like using epoxy to set the plugs, and then they were drawn out, they took some of the surrounding material with them.

In general, the trick with tapered bungs in teak is to tap them in until they're JUST snug, carefully lining up the grain so that when the wood expands/contracts, nothing bad happens, and then chisel off the top, and finally either plane or sand them to match the underlying wood's profile. If you dampen them with just a little varnish on the way in, they seal up quite nicely. I actually know my wood and my goals pretty well --- it's the machining that I needed advice on.
 
brino said:
My first choice would be what @Groundhog suggests and simply turn the part you need rather than a custom cutter to make a part.

My second choice would be to forget trying to modify a hardened, commercial plug cutter and make your own.
Since you need less than a dozen, even unhardened steel should work.
Maybe start with a piece of pipe with an ID that meets the minimum diameter, and cut/grind the taper to suit.
Then using a grinder/dremel cut the gaps for the cutter teeth.

Good Luck and be safe!
Please let us know how you make out.

-brino
Click to expand...

We're thinking along the same lines, Brino -- the first thing I did was look around for a pipe with the right ID...but no joy (at least not in my basement!). Of course, starting with a pipe, I still have to devise a way to chuck it into the drill-press. I've got a long drive to do tonight, so I'll muse a little more...
 
turn a pipe of the desired dimension from a single piece of stock.
reverse the stock in a 4 jaw chuck and indicate true.
turn the drive end of the newly formed blank to a dimension acceptable for your drillpress
relieve and create the cutting edges on the bench or wherever you can
if you make it from O1 you can harden it
 
I agree with Ulma Doctor. I have made several in the past from quick and dirty to all out out of silver steel and hardened for larger batches of plugs. If you turn a slight taper on the inside of the tool it promotes a close fit, and you can compensate for slight size differences by choosing which part of the plug you use (if made "extra long")
The wall thickness of the tool does not need to be thin. In my experience this only leads to quick deformation and dulling of the teeth.
I have also made comparable tools to cut broken screws out of wood and GRP ( inside hole to just clear the screw). To minimize hole size I used a thin wall thickness but these needed touching up of the teeth a lot.( Luckily I usually don't need to a lot of these in the same job....)
Peter
 
How about making the hole bigger in the part you are trying to plug. Make it to a size that will match an available plug cutter. Like doing it on reverse.


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If altering an existing plug cutter dosen't work Iwould try the next size up in metric , something like a 14mm plug cutter, it is 0.55".
 
I finally made my plug-cutter. I drilled out a piece of rod, turned down the OD a bit, then bored it at about a 2.5 degree angle, put a bevel on the cutting end, made a shaft on the other end, and used a collet-block to hold it while cutting four slightly-angled grooves to make cutters. I screwed up the first one by not offsetting it far enough, but the other three came out OK, and I used it to cut a teak plug that came out just as I had hoped, although it turns out I should have used a 1 or 1.5 degree taper --- what I've got is a bit too extreme. But the whole job was surprisingly easier than I'd anticipated, which was great.

Thanks to everyone for the suggestions, etc. It didn't turn out pretty, but it's pretty enough, and I can make a second one a lot faster and better. Here's a picture of the result.


IMG_20180426_222336.jpg
 
Well done Spike7638, the less extreme taper is definitely noticeable, , they look great.
 
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