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Old 11-20-2017, 02:12 PM   #1 (permalink)
 
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Default Ring Hollowing

So recently I started making rings on my lathe with Craft Supplies new ring cores and I love the results. But one thing that I canít seem to do right is get a consistent hole for the ring core. First I take the ring blank and drill a 1/4Ē hole in the center and true it up on a pen mandrel. Then when itís trued up I put on a chuck and I take a square nose scraper to widen the hole. But I realize that as I increase the diameter of the hole, the front hole of the blank is larger than the back hole. So it ends up being a very minor cone shape on the inside and it leaves gaps between the wood and the core. Iíve narrowed down the issue to my technique with the square nose scraper and I was wondering if I need to be doing anything different when Iím cutting that hole. Maybe itís just a matter of keeping the tool sharp or making sure the tool is perpendicular to the blank. Any solutions/suggestions would be greatly appreciated!
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Old 11-20-2017, 03:06 PM   #2 (permalink)
 
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I learned to make boxes from Bonnie Klein many years back. The square scraper per Bonnie is not parallel with the handle. It is canted towards the tip to give relief. The testing tool is either an inside spring compass (ends curved out) or a small steel straight edge.

A bit of practice-check-practice-check and it starts getting easier.
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Old 11-20-2017, 03:45 PM   #3 (permalink)
 
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Quote:
Originally Posted by KenV View Post
A bit of practice-check-practice-check and it starts getting easier.
The cheapest way to do it. I have a set of adjustable reamers, old but still expensive that cuts the time and does an excellent job. You can get the reamer sets on eBay, the better ones that are cheapest are from India. Figure a $100 plus a few more dollars.

Something that I have fooled around with is an adjustable circle cutter for a drill, not to cut the hole, but to use as a guide to the correct diameter. Again this can be a big investment, unless you reset the circle cutter for each size.

Another thought on this, modified spade bits. They are good steel, round the end off to make it work like a spoon bit. Then narrow the sides to the ring sizes. It would take making a bit for each ring size. I tried this, it works, but unless you have access to a good grinder and a steady hand and a lot of luck, plan on messing up a few. But getting it close on both sides will work. Also cut the shaft to about 3" long, and drill a pilot hole to guide the spoon bit. Look at the "chamber spade bits" on this link. Tooling – Vermont Freehand You will also have to grind the sides to make the various ring sizes
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Old 11-20-2017, 05:30 PM   #4 (permalink)
 
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I don't know if this would work or not as I haven't ever made rings but would one of the stepped drill bits work? Or are the steps not wide enough?
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Old 11-21-2017, 01:38 AM   #5 (permalink)
 
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I was going to make the same suggestion as dogcatcher ..... adjustable reamer.

You don't have to buy the whole set for ~$100.

Individual sizes are available if you know what you need. . I get mine at KBCTools.com but there are other places for sure.

You can also buy straight-sided reamers of fixed size at the same place.

Maybe even a twist drill would help you true up the hole once you get close to size . . I think for rings you need bigger drills than for pens and I am wondering what is available close to the sizes you need. . Would have to measure the O.D. of the ring core and compare with readily available drills in that size range.

I just had an idea .... instead of a wood-turning tool, how about using a metal-working tool ..... a boring bar (with a carbide cutting tip) which you could mount in a handle and use it just like the scraper you've been using. . You would not be taking off a lot of material at a time because you would have drilled out the hole with a drill bit of near-correct size (but undersize). . So a fairly long boring bar resting on your tool rest (and mounted in a handle) should do OK. . You can get them with various shapes of tips ... you would probably want a square edge tip and not pointed.

Here is the boring bar page at Grizzly .... kinda expensive, but maybe once you get the idea you can improvise ....

http://www.grizzly.com/search?q=(bor...(boring+OR+bar)

You can even grind your own cutting edge on a HSS (high speed steel, which you can buy) bar like they did in the "old days".

I am rambling .... you can stick with your small scraper and just tweak your technique as Ken said.
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Old 11-21-2017, 04:43 PM   #6 (permalink)
 
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I just ordered the supplies to make some of their rings so haven't done these yet, but I have made rings without inserts before. I use the Forstner bit closest to the ring size but smaller to drill the hole. Get a nice, smooth hole that you can enlarge from there. I'll use my EasyWood Rougher with the square cutter to expand the hole until the insert fits. I have done this same technique making bangle bracelets with metal inserts. For the bangles I have a 2 sets of nylon jaws for my SuperNovaII chuck to hold them as I turn and finish them. One set is set up for expansion and one for contraction depending on what part of the process I'm doing. No chuck marks from them.
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Old 11-22-2017, 10:29 AM   #7 (permalink)
 
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I just ordered a few myself to try. They just came in yesterday, so I won't get to it until after Thursdays holiday. I made a few bentwood's, so I may try and wrap some veneers around it. Also I will try the the solid wood/acrylic method as well. Did you watch craft supplies' video. Seems to me enlarging the hole is the same as enlarging a hole for a shaving brush. Well good luck with them. Carl
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Old 11-22-2017, 02:43 PM   #8 (permalink)
 
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Go to the 2 minute mark on this video
https://youtu.be/m57XbCB3fC4

If you have a metal lathe and can operate it watch this video.
https://youtu.be/DevINpZqOo4 *

Spoon bits are as old as time, they may not be the best, but can be made with tools*that most home shops have access to. It would be expensive to try to make every size, but it could be done. To start you would need to get a drill rod in the correct diameter. The diameter will get the right sized hole, the flat spot, will need to be close to perfect, but close will work, the rounded end, close will also work. With the first video, and a few sets of spade bits, they could be made a lot cheaper. As previously stated, the rounded point, needs to be as close as you can possibly get. Also to keep chatter at a minimum cut the shank to about 3 or 4 inches.

Over the years I have modified quite a few spade bits, it was a case they were the best alternative to an expense trip to the machine shop. The Harbor Freight spade bit set has pretty good steel in it, buy 2 sets and start practicing. A 1" belt sander with a good solid and level table will become your best friend.
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Old 11-22-2017, 09:50 PM   #9 (permalink)
 
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I've made some rings out of corian. Although I wasn't using an insert I had the same problem. I have 2 possible solutions for you that I have used.

Drill it out as close as you can but slightly small and then use an ascillating Spindle sander on the inside to remove the remaining material.

The second option after drilling is a home made turning tool. I took an Allen wrench and ground down the end like a skew. In the scraper position the long point will cleanly remove material from the inside of the ring. I liked this method enough to cut off the curved end of the Allen wrench and make a handle for my mini tool.
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Old 11-22-2017, 11:21 PM   #10 (permalink)
 
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I just had a similar problem. Yesterday I hollowed out the id of the ring blank with a forstner bit. It was close to the od of the ss ring blank so i figured why not my skew to clean up the few mm needed? I took off just a shaving and it was 3 ring sizes too big. It definitely takes a light hand to get the correct size. I have a mini chisel set I bought a long time ago and forgot about:

https://www.amazon.com/PSI-Woodworki...+lathe+chisels

Maybe these would help to make small refinements
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