Cutting Coring Dowels

bruppert

bruppert

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Silver Member
Finally broke down and bought a gun drill so I can core some nice burl I picked up.

Question: I have a bunch of 1" dowels (shaft dowels I don't like). How many passes and how much time should I take to cut them down to roughly .650? Would you take it to size in several passes on the same day or over time with maybe .100 at 1+ week intervals?

Thanks
 
Take down to .100 over first and let them rest for a week or two then cut to
.050 over and do the same. I usually look at them to see if they stay straight or if any turn. The ones that turn I mark and put them aside for a while longer. If they stay straight I cut to about .020 over and let them sit until I need them and then turn the last .030 or .010 undersized and glue them up. The ones that were not straight I let sit for a few more weeks and then cut straight and let them sit another couple of weeks. If they are straight then I cut to .020 oversized and wait until I need them and finish. If they are still warped I toss.

I have 2 gun drills and core to .625 and .750. I core all the way with .625 and then core 3/4 with .750. I also make the dowels the same, 10 inches at .740 and 5 inches at .615.

Hope this helps.
 
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Hi,

Use a very slow feed rate when hogging and on final passes. I have found 6 minutes for 30 inches works for me. You don't want to shock the wood.

Rick
 
Lord help me, I have a plan

Thanks guys!

I'll start with this:

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1" dowel
Turn to .750 - 3 passes (.100, .100 then .050)
Wait 1+ weeks

Turn to .700 - 2 passes
Wait 1+ weeks

Mark if there's any movement
Turn to .670 - 2 passes (if they are really straight I may just do 1 pass)
Wait 1+ weeks

Any movement, Toss them

Final turn to .640 when I need them
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


Do you keep them at 30" or cut them to 15" before you start? Maybe I'll just cut them to 15" now. A little more put and take but probably better in the long run.

Thanks again,
Bryan

Oh, thanks for the PH tip Joey. I was looking at buying some last night. The Camphor Burl I am going to start with is pretty heavy, no spalting and really solid. But, for some of the other wood thats a good idea. Hmmm maybe I'll try 2 or 3 of the CB with PH and have most of the weight in the forearm. Thanks for the idea
 
?

I have another idea. Has anyone tried leaving one end of the dowel larger?

Reason: I've been making the tenon for my A-joint large than .625 I am thinking I may just want to leave about 1.5 inches at one end with a diameter of say .720

Can anyone think of an issue with doing this?

I see one possibly. After turning down and facing that end, I would actually be holding some of it by the burl when assembled, maybe even a small gap. It might only be a 1/4" so maybe a non-issue. Thoughts?
 
Cut them short first, then turn.

It is a little too late but if you had bought an 11/16" or 3/4" drill, the tenon would automatically be too big and the cored wood would be more stable.

You can just leave a big end on the front end of the dowel. Cut a sharp shoulder with a single point cutter leaving extra length on the tenon and pick out which end you're going to use as the joint then glue and assemble.
 
Taking .100 per pass is alittle much but then that depends on what you are cutting with. If it is a shaft machine with table saw it might work ok but with a router with even a six flute .050 is about max.

Yes, I would cut them in 15 inch sections and you can leave the end larger if you want. On my last pass I run twice at .010 undersize.
 
bruppert said:
I have another idea. Has anyone tried leaving one end of the dowel larger?

Reason: I've been making the tenon for my A-joint large than .625 I am thinking I may just want to leave about 1.5 inches at one end with a diameter of say .720

Can anyone think of an issue with doing this?

I see one possibly. After turning down and facing that end, I would actually be holding some of it by the burl when assembled, maybe even a small gap. It might only be a 1/4" so maybe a non-issue. Thoughts?
Click to expand...

First, don't cut them in 30" long unless you want a one-piece core.
On your 30" reject dowels, don't just cut them in half.
Examine the grains and find the best 13-15" lengths.
Cut that good portion then re-center.

After two to three passes, you can leave the bottom oversized .
If take them down to one size top to bottom, you can always sleeve the bottom with a phenolic tube and then that would be your tenon.
Here come the secret police.
 
I thought of buying a .760 GD but wanted the wall thickness on the Forearm thicker than .045 near the joint.
I'll give that some more thought. I do want a thicker wall thickness but it might be better to have the core dowel taking more of the impact. Have to see if I can pickup a GD around .720 (but thats still only approx .065 per side)

I'll cut them to 15"
.050 huh?! Bummer, 5 passes on the first round but I'll start with that. And yes, I am cutting with a router. 2 flute bits. I have a couple of the 6 flute bits but I am saving them. I've yet to find a place to sharpen carbide bits. The one Cutter Grinder I knew retired a year or so ago.

Thanks for another great tip Joey. I hate wasting wood but you're right, the ends of some are pretty bad. I'll keep just the straight section. Better to waste some of the wood than all of it.

Thanks again. Going to the shop to cut some dowels and give the GD more thought.
 
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I use a .750 any time I core. Who cares what the wall thickness is near the joint. .010 is just as good as .500 unless you are using some kind of transparent material as a fore arm. When turning dowels for coring I cut to 15", center the ends and I then take off .225 in one pass. a few weeks before using I check and make final pass to size. If they have moved much between first and second pass I discard.

Dick
 
bruppert said:
I thought of buying a .760 GD but wanted the wall thickness on the Forearm thicker than .045 near the joint.
I'll give that some more thought. I do want a thicker wall thickness but it might be better to have the core dowel taking more of the impact. Have to see if I can pickup a GD around .720 (but thats still only approx .065 per side)
Click to expand...

That's why I step core mine .625 full length and then .750 for 3/4 length or 8 to 9 inches.

It depends on the router and speed for the depth of cut. Mine is cutting at 50 inches a minute with a six flute so I take a smaller bite. You just need to experiment to see how big a cut you can make with your router. A 2 fluke at 10 inches a minute might be able to handle .100 cut.
 
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Just my 2 cents.
A few Newtonian observations.
The deeper you cut, no matter what the tool, the more push off you will have. A 30 inch dowel will push off more than a 15 inch dowel.
Make one cut, then do the pencil mark spiral down the core, then do another cut with out changing settings. You'll see!

Personally I believe 1 or 2 weeks may be too short a time to let the wood
move.

I don't think you can scare wood by cutting it fast.

If a burl is so soft you are afraid to clamp on it. You might want to
stabilize it.
 
cutter said:
Just my 2 cents.
A few Newtonian observations.
The deeper you cut, no matter what the tool, the more push off you will have. A 30 inch dowel will push off more than a 15 inch dowel.
Make one cut, then do the pencil mark spiral down the core, then do another cut with out changing settings. You'll see!

Personally I believe 1 or 2 weeks may be too short a time to let the wood
move.

I don't think you can scare wood by cutting it fast.

If a burl is so soft you are afraid to clamp on it. You might want to
stabilize it.
Click to expand...

I heard you cut shafts in a separate room so others can't hear them scream.
 
Brickcues said:
That's why I step core mine .625 full length and then .750 for 3/4 length or 8 to 9 inches.

It depends on the router and speed for the depth of cut. Mine is cutting at 50 inches a minute with a six flute so I take a smaller bite. You just need to experiment to see how big a cut you can make with your router. A 2 fluke at 10 inches a minute might be able to handle .100 cut.
Click to expand...

Nice, I didn't think of that. Making a stepped dowel and doing the same thing with the bored hole. Obviously more work but I really like that idea. The only issue I see is where the dowel's step meets the internal face of the bore... seems like you could have a fair amount of space there. The space isn't really the issue, more the amount glue you'd have there. I'll be using Gorilla glue and that stuff really expands so I'd be a little worried about it possibly cracking the Burl at that spot. Have you had any issues with this? Do you do a flat face or chamfer it to roughly the same angle as the drill?

Either way, I see another GD in my future.


Steve, you're right about the push off but it would depend on how your cutting as to how far.

I cut my shafts with the router horizontal so I am cutting only with the very end of the bit. I get almost zero chatter.

Cutting with the side of the router bit it pushes more. Creates more pressure. When I tried this I got more chatter, especially in the middle. I saw no benefit in doing it this way.

Cutting with a lathe bit would be much more pressure. I was playing around one day and tried cutting the length of a shaft with a lathe bit.... and lets just say I won't try that again.


When I am hogging material off for a handle or cleaniung up squares I usually do the first pass or 2 taking off .100 (.050 per side). Its less than a 1/16" cut and as long as I don't try to push it too fast I don't have any problems. I pressure spin it so if it stalls then I know I am going much too fast.

Oh, the burl is pretty hard. The only thing I am worried about is the glue building up so much pressure it cracks, either right away or later when I am finshing it to size.... moreso the later
 
coring dowels

I buy 1 in shaft dowels and immediately cut them to .750. I hang them for a month or 2 before using. If they move, I reject them. I get push off in the middle of about .010 when I turn them. I use an 11/16 gun drill (.6876) I turn my dowels to about .670 or so and sand them with 60 grit for an easy slip fit.

I get them from a good source that knows how to dry wood and I have very few rejects.

I haven't had any cues warp.

Kim
 
whammo57 said:
I buy 1 in shaft dowels and immediately cut them to .750. I hang them for a month or 2 before using. If they move, I reject them. I get push off in the middle of about .010 when I turn them. I use an 11/16 gun drill (.6876) I turn my dowels to about .670 or so and sand them with 60 grit for an easy slip fit.

I get them from a good source that knows how to dry wood and I have very few rejects.

I haven't had any cues warp.

Kim
Click to expand...
That's a lot of clearance I think Kim.
.010" should be plenty.
.015" a ton.
.017+ is a lot of foam.
 
The router bit steps out at about the same angle as the gun drill so there is little gap. I do not like G glue but use West System Epoxy and coat both the female and male parts to make sure of good glue contact between both and to fill any gaps. Been doing this for years and have not had any problems.
 
JoeyInCali said:
That's a lot of clearance I think Kim.
.010" should be plenty.
.015" a ton.
.017+ is a lot of foam.
Click to expand...

It is a little more than I would like but, I have tried about .010" and it gets pretty sticky about half way through. I sometimes core a full 30 in piece. I don't have a lot of foam inside. I cut rings in the dowel and put enough GG in the tube so that it comes out the other end when I push the dowel through in a twisting motion. I think it's almost solid glue. I have cut them apart and I can't see any internal foam in the joint between the cored piece and the dowel. It foams out the ends and sometimes through a pore in the wood. I think GG only foams where it has no pressure and there is a gap. If you fill a small gap with GG and there is pressure, I don't think there is really any foam except where it escapes to the atmosphere. It rings when I bounce it on the floor. I have never had a problem.



Kim
 
whammo57 said:
It is a little more than I would like but, I have tried about .010" and it gets pretty sticky about half way through. I sometimes core a full 30 in piece. I don't have a lot of foam inside. I cut rings in the dowel and put enough GG in the tube so that it comes out the other end when I push the dowel through in a twisting motion. I think it's almost solid glue. I have cut them apart and I can't see any internal foam in the joint between the cored piece and the dowel. It foams out the ends and sometimes through a pore in the wood. I think GG only foams where it has no pressure and there is a gap. If you fill a small gap with GG and there is pressure, I don't think there is really any foam except where it escapes to the atmosphere. It rings when I bounce it on the floor. I have never had a problem.



Kim
Click to expand...
Indicate your gun drill near the tip down to 12" from the tip.
I think it's off.
If it's a tailstock mounted one, your tailstock is off.
Mine is tool post mounted one.
I stick a magnetic base indicator on the bed near the chuck.
I indicate the side of the drill.
I get within 2 thou the length of the rod to be drilled.
I power bore the entry and exit holes first before gun drilling.
.008" total clearance is plenty for me.
 
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