Cutter to Use on Deluxe Lathe

[Naked Cues]

Howdy guys,

I've been trying to cut purpleheart shafts on my HT Deluxe. The cutters I've tried all "grab" the shaft in the middle of the pass, cause vibration, and then either push the piece so hard it bounces back and the cutter digs almost all the way through it or cuts inconsistently and leaves me with a ton of sanding to do.

I've tried putting the router both vertical and horizontal with 1/4" carbide end mill (three flutes), 1/2" straight cutting bit (two flutes), and a 1/2" cutter (one flute)...they all do the same thing.

*I cut from right to left
*Have tried taking passes from 0.010" to 0.025"
*Tried all available speeds the lathe will do.

The purpleheart is 30" long and the vibration starts when it gets under ~.650"

Maple cuts OK with the two flute 1/2" straight cutter and the router in the vertical (not horizontal) position.

Any suggestions would be great. I've read about other machinery used to turn shafts...but I need to accomplish this with the Deluxe.

Thanks,
Jason.

Link to image if insert doesn't work: http://i1182.photobucket.com/albums/x449/nakedcues/100_4309.jpg

 

[GBCues]

I'm guessing you are spinning the lathe too fast - the piece only needs to turn at about 300-400rpm and a nice slow pass.

How much are you trying to take off in a single pass? .05" is a pretty good rule-of-thumb maximum.

My 2 cents,

Gary

Edit: Oops, I see you are well under .05 per pass

 

[JoeyInCali]

What's the TIR of your router ?

 

[LGSM3]

how much tailstock pressure are you using, where is your cutter oriented relative to the center line of cue?

 

[whammo57]

Howdy guys,

I've been trying to cut purpleheart shafts on my HT Deluxe. The cutters I've tried all "grab" the shaft in the middle of the pass, cause vibration, and then either push the piece so hard it bounces back and the cutter digs almost all the way through it or cuts inconsistently and leaves me with a ton of sanding to do.

I've tried putting the router both vertical and horizontal with 1/4" carbide end mill (three flutes), 1/2" straight cutting bit (two flutes), and a 1/2" cutter (one flute)...they all do the same thing.

*I cut from right to left
*Have tried taking passes from 0.010" to 0.025"
*Tried all available speeds the lathe will do.


The purpleheart is 30" long and the vibration starts when it gets under ~.650"

Maple cuts OK with the two flute 1/2" straight cutter and the router in the vertical (not horizontal) position.

Any suggestions would be great. I've read about other machinery used to turn shafts...but I need to accomplish this with the Deluxe.

Thanks,
Jason.

Link to image if insert doesn't work: http://i1182.photobucket.com/albums/x449/nakedcues/100_4309.jpg

I cut PH shafts and coring dowels on my hightower and never had a problem. Get a live center with a spring point. Only hold the piece with the spring. Vertical router .... 3/4 straight bit.. make sure the bit is sharp.. is it carbide? . lathe on the slowest speed... about 5 inches/min feed rate on final cut.

Try to wiggle the router after you set it up. Everything should be pretty tight. If not ... fix it before cutting.

It should work just fine or there is something wrong.

Kim

 

[cueman]

The 3/4" carbide bit that comes with the lathe, either vertical or horizontal run on slower speed should cut fine.

 

[Naked Cues]

how much tailstock pressure are you using, where is your cutter oriented relative to the center line of cue?

Thanks everyone for the replies. I'm not sure of my router's runout Joey...I'll throw a gauge on it when I get home.

I've ordered a Taig spring loaded live center (Thanks LG & Kim) since I suspect I may be cranking down too hard on the tailstock and warping the wood as the diameter shrinks. I'll also pick up a new 3/4" carbide cutter (Thanks Cueman) and slow the lathe down to minimum speed (Thanks GB)...I had a tendency to think a higher speed would fix the issue...so I may just been adding to the problem.

Thanks again...I'm off to buy more parts...jeez what a great hobby...

-Jason.

 

[danutz]

You may want to pick one of these up. http://www.cuecomponents.com/smcu6flrobla.html

 

[Thomas Wayne]

Over the years I've experimented with almost every tapering configuration you can imagine. Ultimately the quality of a finish cut is primarily determined by the combination of "feed and speed" - that is, feed rate of the router carriage and speed of the headstock. The right combination is unique to each shaft machine, and can only be determined by trial and error on YOUR machine.

That said, I've also found I get the best cuts using a very thin profile two-flute blade - and believe me, I've tried every combination available before I discovered this. The cutters I use are essentially "slotting bits" (though I have them custom made), and they are 1/16th inch thick. I believe a wider, "beefier" cutter profile inherently produces more tool pushoff, which results in harmonic vibrations at the worst possible location - the middle of the shaft.

Also, you want your blades to be RAZOR sharp; don't be too cheap to replace them when they lose their edge.

FYI, I've gone down to as thin as 1/32" on my cutting blades, but could not detect any appreciable difference from 1/16". I realize this is nowhere as easy or convenient as running down to your local Home Depot and buying a stock 3/4" router bit off the shelf, but that's what works for me...

Think of it this way - just as a shaft with a heavy front end will deflect the cueball more than a lighter (or even hollow) tip, so the beefy cutter bits will deflect a shaft. The problem is, the shaft will spring back into the cutter, causing exactly the damage you're experiencing. By contrast, a very thin cutter will simply slice into the surface of the shaft without deflecting it nearly as much.

TW

 

[ChampionsRepair]

Over the years I've experimented with almost every tapering configuration you can imagine. Ultimately the quality of a finish cut is primarily determined by the combination of "feed and speed" - that is, feed rate of the router carriage and speed of the headstock. The right combination is unique to each shaft machine, and can only be determined by trial and error on YOUR machine.

You also need to account for the rpm of the router in relation to the diameter of the bit to control the surface speed of the cutting surface.

That said, I've also found I get the best cuts using a very thin profile two-flute blade - and believe me, I've tried every combination available before I discovered this. The cutters I use are essentially "slotting bits" (though I have them custom made), and they are 1/16th inch thick. I believe a wider, "beefier" cutter profile inherently produces more tool pushoff, which results in harmonic vibrations at the worst possible location - the middle of the shaft.

This is only true with an increase of mass. Assuming the same style bit, yes. You can accomplish the same thing with a T-slot cutting bit and reducing the rpm of the router. This reduces the mass of the bit even further.

Also, you want your blades to be RAZOR sharp; don't be too cheap to replace them when they lose their edge.

FYI, I've gone down to as thin as 1/32" on my cutting blades, but could not detect any appreciable difference from 1/16". I realize this is nowhere as easy or convenient as running down to your local Home Depot and buying a stock 3/4" router bit off the shelf, but that's what works for me...

HD carries T-slot bits intended for a 1/4" slot kerf. So does Lowes, Ace hardware, Sears and True Value. They come in handy for making jigs for use elsewhere in the shop too!

Think of it this way - just as a shaft with a heavy front end will deflect the cueball more than a lighter (or even hollow) tip, so the beefy cutter bits will deflect a shaft. The problem is, the shaft will spring back into the cutter, causing exactly the damage you're experiencing. By contrast, a very thin cutter will simply slice into the surface of the shaft without deflecting it nearly as much.

TW

The 1/4" T-slot bit will reduce mass even further than your 1/16" slot wing cutter. The unintended force exerted to the work piece will be reduced similarly. And they will cost a small fraction of having custom tooling manufactured. Just reduce the rpm of your router to attain the same surface speed of your current setup. The wood will never know you are saving money.

 

[JoeyInCali]

The 1/4" T-slot bit will reduce mass even further than your 1/16" slot wing cutter. The unintended force exerted to the work piece will be reduced similarly. And they will cost a small fraction of having custom tooling manufactured. Just reduce the rpm of your router to attain the same surface speed of your current setup. The wood will never know you are saving money.

CR, how would a 1/4 slot cutter's less mass than the wing cutter have any effect ?
3-wing or 4-wing slot cutters are not that expensive btw and can be re-sharpened. They also have a larger OD if it mattered.
They do need to be OD'd when getting sharpened b/c the tips aren't even lengths from the factory.
Thanks

 

[ChampionsRepair]

CR, how would a 1/4 slot cutter's less mass than the wing cutter have any effect ?

F=M x V, in and of itself the effect of the mass on the force exerted on the work piece is small. As the required velocity is also less due to the diameter of the bit, the cumulative gain is worth while. I use a T-slot bit that has a 3/4" diameter of cut, the mass of a 1/4" 2 flute straight bit with a 1/2" depth of cut. The weight of my bit is about 1/4 of the 1/4" slot wing cutter I used to use. I can take half again deeper cuts with the same results I used to obtain.

 

[Thomas Wayne]

You also need to account for the rpm of the router in relation to the diameter of the bit to control the surface speed of the cutting surface.

Most run-of-the-mill routers have fixed speeds, and would require some sort of external control to change that. Not MY routers, since I use variable frequency drives throughout the shop, but most of those used on the home/hobby equipment prevalent around these parts are not easily set up for Precise (pun intended) rpm control. More importantly - your argument notwithstanding - trial and error experimentation can still result in a feedrate/headstock-rpm ratio that will balance with a particular router head speed, and usually the feedrate & headstock are more easily controlled.

This is only true with an increase of mass. Assuming the same style bit, yes. You can accomplish the same thing with a T-slot cutting bit and reducing the rpm of the router. This reduces the mass of the bit even further.

HD carries T-slot bits intended for a 1/4" slot kerf. So does Lowes, Ace hardware, Sears and True Value. They come in handy for making jigs for use elsewhere in the shop too!

Cutter mass is irrelevant. It's the size of the cutting edge [presented to the work surface] that determines stock pushoff. Presumably any decent shaft turning setup will have a very rigid cutting spindle, so the only thing to push the shaft away (instead of cleanly cutting it) would be the resistance of the wood surface to the penetration of the cutter. Beyond any shadow of a doubt, the smaller and sharper the cutting edge is the more easily it will penetrate the wood (rather than push it away).

Mass [of the cutter] has NOTHING to do with it.

Sorry if the shaft-tip mass analogy confused you, but it was just that - an analogy. Wasn't meant to exactly parallel the choice-of-cutter-head issue.

TW
(PS: One other factor in stock pushoff can be air pressure generated by the cutter head. This is more likely to cause inaccurate finished diameters than the type of problems raised by the OP, but might still be something to consider.)

 

[JoeyInCali]

F=M x V, in and of itself the effect of the mass on the force exerted on the work piece is small. As the required velocity is also less due to the diameter of the bit, the cumulative gain is worth while. I use a T-slot bit that has a 3/4" diameter of cut, the mass of a 1/4" 2 flute straight bit with a 1/2" depth of cut. The weight of my bit is about 1/4 of the 1/4" slot wing cutter I used to use. I can take half again deeper cuts with the same results I used to obtain.

I still don't get how the weight has any impact on how clean the cuts are.
Table saw blades are a ton heavier but at 1/8 kerf, they have less pushoff than the regular wing cutters I think due to frequency of cuts.
Wing cutters' interrupted cuts ( the contact with wood has an interval ) might be another factor how clean the cuts are.
I get mine grind with a little relief so the tips " scoop " on the wood instead of gouging it. But that can be just mental.

 

[hdgis1]

Im curious as to whether anyone has used a stationary cutter to perform these operations. From my experiences turning bowls and such, one can get one hell of a smooth cut using a standard skew...

Chris

 

[cueman]

Im curious as to whether anyone has used a stationary cutter to perform these operations. From my experiences turning bowls and such, one can get one hell of a smooth cut using a standard skew...

Chris

I used to use skews and other wood turning tools to build cues. Yes you can get a good clean cut if you can keep the push off from happening. I use to wrap a loop of leather around the shaft and move it along with the tool to keep down on the whipping and gouging.

 

[JoeyInCali]

Im curious as to whether anyone has used a stationary cutter to perform these operations. From my experiences turning bowls and such, one can get one hell of a smooth cut using a standard skew...

Chris

How much tolerance can you hold ?

 

[hdgis1]

How much tolerance can you hold ?

Im not talking about holding the thing in your hand for crying out loud! Think something along the lines of using your carbide tipped cutter in the QCTP to cut down the diameter of a ferrule. Cant imagine the tolerances would be any worse than a spinning router bit beating against a shaft.

Chris

 

[hdgis1]

I used to use skews and other wood turning tools to build cues. Yes you can get a good clean cut if you can keep the push off from happening. I use to wrap a loop of leather around the shaft and move it along with the tool to keep down on the whipping and gouging.

Chris - Does using router bits help avoid the push off?

Chris

 

[JoeyInCali]

Im not talking about holding the thing in your hand for crying out loud! Think something along the lines of using your carbide tipped cutter in the QCTP to cut down the diameter of a ferrule. Cant imagine the tolerances would be any worse than a spinning router bit beating against a shaft.

Chris

It'd be too slow.
It was done in the old days before routers came about.