Butt tapering - issue cutting ivorine 4 joint collar and metal rings

J

JohnsonJ

Member
Hello all,

I just attempted to taper my first sneaky conversion butt, and would kindly welcome a pointer in the right direction, as it didn't go too well. It was quite catastrophic 😆.

I'm using a 4 wing carbide cutter in my router at 30k RPM, 800W, and while it cuts wood amazingly well, I could not cut ivorine for the life of me.

With a depth of cut of 0.05mm/0.002in per side, I tried running the lathe both at 300 and 1200 RPM, with the router feed rate going from extremely slow, to extremely fast, and everything in between at both RPM ranges of the lathe, conventional and unconventional milling. The metal rings were cut nicely at a slow router feed rate, but once it got to the ivorine 4, it started to heat it up excessively. Speeding things up did lower the heat buildup by quite a bit, but the cut quality went down exponentially, while still being too hot. So basically, at a low feed rate, the copper rings were cut perfectly, the ivorine badly and overheated, whilst at a high feed rate, both were cut badly, and the ivorine still overheated...

I started off with a relatively fresh cutter (it turned maybe 15 dowels in total before), and the router is very rigidly mounted to my lathe cross slide. I wasn't getting any harmonics/deflection due to the RPMs, the quality of the cut was just simply bad, and the cutter ruined at the end of this experiment.

I'm now thinking on what might have caused it, and having doubts if the 4-wing cutter even is an appropriate tool for cutting ivorine 4 collars. It didn't make an acceptable cut on the ivorine even on the first pass.

One (partial) solution is to either find or make a set of better quality collets for my router, since the ones I have right now aren't as concentric as they should be, but regarding the specific issue at hand, I doubt this would fix my issue, it might just prevent a little less heat build up... which would still be about 500% too high.

Or can ivorine 4 not be cut with a 4-winged router bit at all, and I must turn it down on the lathe and then just match the wooden part to it? Or maybe use some different type of cutter?

Looking forward to your replies, thanks 😊
 
You should have no problem cutting Ivorine, I suspect it's either the way you are cutting or your cutter is toast. Slow RPM and slow feed rate, try taking lighter passes. Any pictures of your cutter and setup?
 
https://imgur.com/a/wghJJ32

That's my setup, with the cutter I tried to taper with.

I'll try hooking up a potentiometer to the router and see how that goes, I didn't even think about the router rpm being a factor, since it's a simple on/off 30k rpm type deal. But it does make perfect sense now that you mention it...

I was thinking that the higher the rpm the better, and that 70-80% of the heat would get thrown out of the workpiece by the chip. But I guess not with plastic. Wood didn't heat up much though, and it cut it very, very nicely. I will check the temperatures on wood at 9k and 30k, and post back here, it's gotten me curious now.

I'll try to shoot for 9k with the pot and verify it with a digital tachometer. I will also simultaneously upgrade the collets to tighter toleranced ones. Will update when I get everything sorted.

Thank you very much!
 
It is all about chip loading. Your feed rates are based on chip per tooth in relation to rpm. Too slow a feed rate in relation to rpm will create more heat. What is your feed rate set at on the machine? Also pay attention to tool height. You should set your cutter so the top of the tooth is on the center line. Some people make the mistake of cutting with tooth set so they are cutting half way up. This creates a situation where you have a lot of tool engagement with the part. This will also lead to more chatter.
 
I don't see anything supporting the end of that dowel. Is it just free hanging and only supported by the chuck? I can see the tailstock with an empty quill at the other end of the lathe. The dowel should be supported on the tail end with a live center.
 
If you were really cutting without TS support on a long extension, that would seem to be a large part of the issue?

If you had adequate support and were cutting metal, plastic, and wood all in the same pass with the same cutter, it is possible that the carbide chipped or dulled on the metal, but can still cut fine with the negative rake(dullness) introduced on the tool edge, but will beat and heat the plastic parts.

Slow down the router as others already mentioned, slow down the feed, use TS support, and try a brand-new cutter (or sharpen the one in use).

FWIW, i've set difficult sleeves with mixed metal, phenolic, other plastics up on the surface grinder or tool and cutter grinder and ground them with mist. Then fit/glued to the butt with very minimal further shaping/sizing required.

FWIW#2 - whatever it is, with rings and metal you can't be calling it a sneaky!
:D

smt
 
Canadian cue said:
It is all about chip loading. Your feed rates are based on chip per tooth in relation to rpm. Too slow a feed rate in relation to rpm will create more heat. What is your feed rate set at on the machine? Also pay attention to tool height. You should set your cutter so the top of the tooth is on the center line. Some people make the mistake of cutting with tooth set so they are cutting half way up. This creates a situation where you have a lot of tool engagement with the part. This will also lead to more chatter.
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The top of the tooth on the centerline, with the workpiece rotating down into the tooth, or up away from it?

I had it centered exactly, but I will also try your method. Still need to source some quality collets, I did manage to hook up a board with a pot so I can control RPM on the router now though, so I will attempt again at the start of next week probably.

My parameters were variable, from the lathe 300 RPM to 1000, with a feed rate of the router of 0.04-0.30mm/rev (0.0016-0.01in/rev). The router RPM was fixed at 30k, I'll be running it lower this time.

GBCues said:
I don't see anything supporting the end of that dowel. Is it just free hanging and only supported by the chuck? I can see the tailstock with an empty quill at the other end of the lathe. The dowel should be supported on the tail end with a live center.
Click to expand...
That was an unrelated photo to show my setup, since other members wanted to see how I have the router set up. The cue was of course supported with a live end in the tailstock, no worries about that. The setup is good, on a 80cm (31.5in) long wooden dowel I get the diameters on both ends to be within 0.01mm (0.0004in), maybe less if I really tried. So no issues regarding the support of the workpiece. Which is why I was very confused on the ivorine chatter/burning, but I didn't realize others aren't running their routers at 30k rpm, I assumed it was the ''standard'', since the router I picked up didn't come with any rpm control to begin with.

Ssonerai said:
If you were really cutting without TS support on a long extension, that would seem to be a large part of the issue?

If you had adequate support and were cutting metal, plastic, and wood all in the same pass with the same cutter, it is possible that the carbide chipped or dulled on the metal, but can still cut fine with the negative rake(dullness) introduced on the tool edge, but will beat and heat the plastic parts.

Slow down the router as others already mentioned, slow down the feed, use TS support, and try a brand-new cutter (or sharpen the one in use).

FWIW, i've set difficult sleeves with mixed metal, phenolic, other plastics up on the surface grinder or tool and cutter grinder and ground them with mist. Then fit/glued to the butt with very minimal further shaping/sizing required.

FWIW#2 - whatever it is, with rings and metal you can't be calling it a sneaky!
:D

smt
Click to expand...
I will do a second try in the following days, I'm almost certain the lower router rpm will solve most of the issue, if not, I will probably think about turning the rings/joints down with the tungsten carbide cutting knife, and then just trying a light finishing pass over everything. If it works out I'll just call it a Pete then, since it will have ivorine and rings for sure :D.

I was also thinking of blowing air on it whilst it's cutting to help cool it, I've got a few options now to try, and will try them all, measure their success, and update back.

One thing I did notice was that the copper chips were flying like crazy and basically lodging themselves in my garage uniform... is this common even when properly setup? Also, is there a chance of the brazed tungsten tooth flying off the cutter? With the speed and density it's got going, it would probably be worse than getting shot.... am thinking about making some protective polycarbonate casing around the router just in case something flies off...


Thank you all very much for your kind suggestions, I'll give an update shortly on how my second attempt goes.

I'm feeling very optimistic, the only thing really holding me back now is me wanting to cut live threads on the joint and buttcap, but I'm unable to do so at the moment, as the thread cutter is out of line due to bad collets (which probably also doesn't help my tapering 4 wing cutter). Since I really want to have those pieces threaded on the cue, but not wanting to wait the month or so to get the collets (as I want to see the taper RIGHT NOW 😅), I'll probably go ahead and cut a wire thread in both of them, and show a pic or two of the next tapering attempt in a few days.

I can already see the next setup goal being some type of vacuum/dust extractor setup, and I've only cut a few dowels so far.
 
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lso, is there a chance of the brazed tungsten tooth flying off the cutter
Click to expand...

It has happened.
But far more commonly the tooth breaks, so less than a full tip flying at you.
Trusting you at least always wear eye protection for any sort of chip?
And keep important body parts well below the line of radial fire?

A friend once told me that another friend's dad lost an eye to starting up a new carbide tipped saw blade without face protection.
The warning it good enough i never verified it. (Sometimes as a kid you hear things that were not quite how it happened, although the fact of more or less severe eye injury was true)

Safety, including respiratory, is a good practice so you can keep doing all the things you love into a healthy old age.
 
JohnsonJ said:
The top of the tooth on the centerline, with the workpiece rotating down into the tooth, or up away from it?

If you are turning the spindle in a conventional manner as in counterclockwise, yes. The idea is to set it up like you would if you were using a single point tool or turning conventionally.
Click to expand...
 
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