Bushing quality

[redfishsc]

Anyone know what they make the bushings out of? Is it high-carbon steel?

Anyhow, I just made a string of American pens (6) and the last few have lousy joints in one particular spot. I know I am hard on the bushings, I'm learning how to stay off of them with the skew and sandpaper.


Seems to me that if they were to make them out of HSS they'd last a good bit longer and shouldn't cost a terrible bit more.

 

[Dario]

There was a lengthy discussion about this and if memory serves me right, harder is not always better (for bushing that is [])

 

[chigdon]

Maybe not, but for our machinest out there I have a question. Would it be better to have a mandrel that was made from something along the lines of titanium so that it would not flex as easily under pressure? I would be interested if so!

 

[Dario]

Originally posted by chigdon
<br />Maybe not, but for our machinest out there I have a question. Would it be better to have a mandrel that was made from something along the lines of titanium so that it would not flex as easily under pressure? I would be interested if so!

Me too...even better if it can be made shorter for single barrel turning...but I most likely cannot afford it. [V]

 

[Paul in OKC]

Originally posted by Dario
<br />

Originally posted by chigdon
<br />Maybe not, but for our machinest out there I have a question. Would it be better to have a mandrel that was made from something along the lines of titanium so that it would not flex as easily under pressure? I would be interested if so!

Me too...even better if it can be made shorter for single barrel turning...but I most likely cannot afford it. [V]

I don't think titanium would be any better on the flex end than current. I have made a mandrel or two out of drill rod. The biggest problem is the length needed with such a small diameter rod. Don't think there is much way around that. As for bushings, they might be made of something like 4140. I would say most likely just regular cold rolled steel, but not sure.

 

[ctEaglesc]

Put a light coat of CA on the bushings(it will usually wind up on them when if you apply it to the barrel of the pen.)
This also stops the blanks from turning grey from the bushings while sanding.
As far as the mandrel bending, how sharp are your tools?
I don't mean that sarcastically but there shouldn't be that much resistance if your tools are sharp.
On the herringbone pen I made I needed some pinchucks. I made them from 1/4x28 bolts from the hardware store and corian.Then again I don't sharpen with a grinding wheel Iuse a diamond stone.

 

[mrcook4570]

Originally posted by redfishsc
<br />and the last few have lousy joints in one particular spot. I

Are you trimming the blanks exactly perpendicular to the tube? This could be the cause of the poor fit. Other possibilities - bent mandrel, overtightening lock nut, etc. Try rotating blanks (with bushings stationary) 90 degrees several times while sanding.

 

[bonefish]

Titianium is very strong, but it is also springy. I don't think it would be any better than what we have, if as good.

I have looked into buying some precision ground hardened steel rod, but so far, I haven't been able to find it in .247 dia. .250 is the
closest I have found, and it is slightly too large to go into the bushing.

Speaking of short ones. I have a set of HF transfer punches and the 1/4 inch one will go into all of the bushings I have tried, and with a snugger fit than the factory mandrells.

I don't know the hardness of these punches, but I would think it would have to be hard and stiff to use as a punch. They also appear to be straight.

The problem is, it is not threaded. Near the top of my to-do list is trying to thread it, but a threading die might not do it.

These punches are about 5 inches long, long enough to turn one barrel at a time.

If this works, and I am able to thread it, would there be enough demand to make it worth while to make a bunch of them? I'm not sure if you can purchase only 1/4 inch ones or if you would have to buy the set.

The cost would depend on the price of the punches, and the difficulty in threading it, and also on the difficulty of making a counter bore for the tailstock.

Bonefish

 

[wdcav1952]

I think Eagle made the best point on this thread. If you are trying to push a cutting tool through the back of the blank, you will bend the mandrel. Your mantra should be "Sharp tools, light cuts!"

 

[redfishsc]

My problem was the fact that I wore out the bushings. I'm still learning how to keep my skew and gouge off the bushing. I slapped a digital micrometer on the suspect bushing for this particular pen and they came out to .483" while the part it matched up to was .492", and I know for a fact the bushing was the right diameter to begin with. I know I've milled it down by accident.



Anyhow, if someone wants to turn one barrel at a time, someone (Dario, I think) mentioned how to do it. Rough both blanks out on the mandrel but then remove them and mount them between a 60* dead center (headstock) and a 60* live center (tail stock). This will only work with pens that have tubes that ride the bushing, won't work with slimlines. I have yet to try it but I don't see where that wouldn't work.




As far as bushing material, can someone point me to that discussion? Why wouldn't hardened M2 HSS make a more durable bushing? Seems like your HSS chisel wouldn't gore up it's own type as easily as it does bread-n-butter cold rolled steel.

 

[Yarael]

Well as I am just starting in this addiction I havent had an problems with the mandrel bending. But in my experience Titianium tends not to bend/flex as much as shatter when you reach its limit. It will bend somewhat then it just breaks. Doesnt stay bent. And for cost worth it really is not worth it. Titianium may be strong but if you push it just right it snaps. And the limits tend to be just right. It will bend a tad then it just breaks. Not much of inbetween. Its one or the other.

 

[JimQ]

As to harder bushings, which would you rather replace, bushings or chisels? They are made of softer steel for a reason! If you hit HHS bushings you would rapid remove the edge on your chisel. Milder steel gives a little and is a "little" kinder.

JimQ

 

[ctEaglesc]

Anyhow, if someone wants to turn one barrel at a time, someone (Dario, I think) mentioned how to do it. Rough both blanks out on the mandrel but then remove them and mount them between a 60* dead center (headstock) and a 60* live center (tail stock). This will only work with pens that have tubes that ride the bushing, won't work with slimlines. I have yet to try it but I don't see where that wouldn't work.

I read that but would never try it.
Too much chance of applying too much pressure enlarging the tube and splitting the blank.I have had a live ceneter point act as a wedge and split a glue up, same principle.If it seems it would help you for some reason go for it, I'll pass.Too much time invested at this point to risk damaging what it close to a finished pen.

As far as bushing material, can someone point me to that discussion? Why wouldn't hardened M2 HSS make a more durable bushing? Seems like your HSS chisel wouldn't gore up it's own type as easily as it does bread-n-butter cold rolled steel.

You are not supposed to use the chisel on the bushings to begin with.[]A while back I decided that my glasses did not have the right focal distance for working on the lathe.
I now use the headset magifier from HF for $4.99 when ever I work at the lathe.
On the home page there is an aricle about making bushings out of Corian.That would seem like it is the opposite end of the spectrum.I'll stay in the middle with what I can buy with the kits.(I have made bushings out of brass and plastic bread board stuff.Some use Delrin.It doesn't seem there is a need for harder bushing otherwise the Mfgr's would have already done it and priced them accordingly[]

 

[Paul in OKC]

I have looked into buying some precision ground hardened steel rod, but so far, I haven't been able to find it in .247 dia. .250 is the
closest I have found, and it is slightly too large to go into the bushing.

Bonefish

MSC carries letter 'D' drill rod. It is .246 diameter.

 

[RussFairfield]

My issue with bushings has always been dinensional tolerances, or lack of them, rather thqn what they are made from.

I agree with Eagle on not using the centers directly on the brass tube. You can eliminate this problem with the 7mm tubes by using a short length of rod to support a bushing at each end. Just make sure it is short enough that the centers bottom out on the bushing and not the rod. A 1/4" bolt and a hacksaw make this an easy task.

Being able to turn one barrel at a time is another argument in favor of the collet chuck. This is a definite factor for turning the larger pens where runout and tolerances get magnified. For the serious pen turner, it is the best investment you will ever make.

 

[Mudder]

Originally posted by Paul in OKC
<br />

I have looked into buying some precision ground hardened steel rod, but so far, I haven't been able to find it in .247 dia. .250 is the
closest I have found, and it is slightly too large to go into the bushing.

Bonefish

MSC carries letter 'D' drill rod. It is .246 diameter.

I have always wondered of spline shafting would work for this type of application. It is slightly more ridged than round shafting but I'm afraid that the cost would offset the benefit.

 

[Paul in OKC]

Originally posted by Mudder
<br />

Originally posted by Paul in OKC
<br />

I have looked into buying some precision ground hardened steel rod, but so far, I haven't been able to find it in .247 dia. .250 is the
closest I have found, and it is slightly too large to go into the bushing.

Bonefish

MSC carries letter 'D' drill rod. It is .246 diameter.

I have always wondered of spline shafting would work for this type of application. It is slightly more ridged than round shafting but I'm afraid that the cost would offset the benefit.

Interesting thought. The are a couple of places that sell splined rod to make small gears. Might have to check it out. One place I can think of is SPI-something. I have it in my favorites on another computer. If there was some small tubing with at least a 1/16" wall might work as well. Tubing is sometimes more rigid than bar.

 

[bonefish]

Paul, is MDC McMaster Carr?

A note in favor of hard bushings.

When you get close to the correct size, a hard bushing might prevent turning the pen body too small on the bushing ends.

A hardened bushing would probably dull a lathe tool, but also one made from hot or cold rolled steel will dull the tool, too. Maybe not as much, but it will.

If I were going to make them, I wouldn't use M2. I would use D2 at about RC60, because it is more abrasive resistant.

Back to mandrells. You don't have to press all that hard with the lathe tool to distort the mandrell. Just normal pressure won't bend it, but it will cause it to deflect.

Bonefish

 

[Paul in OKC]

Originally posted by bonefish
<br />Paul, is MDC McMaster Carr?

A note in favor of hard bushings.

When you get close to the correct size, a hard bushing might prevent turning the pen body too small on the bushing ends.

A hardened bushing would probably dull a lathe tool, but also one made from hot or cold rolled steel will dull the tool, too. Maybe not as much, but it will.

If I were going to make them, I wouldn't use M2. I would use D2 at about RC60, because it is more abrasive resistant.

Back to mandrells. You don't have to press all that hard with the lathe tool to distort the mandrell. Just normal pressure won't bend it, but it will cause it to deflect.

Bonefish

MSC. www.mscdirect.com

 

[redfishsc]

I read that but would never try it.
Too much chance of applying too much pressure enlarging the tube and splitting the blank.I have had a live ceneter point act as a wedge and split a glue up, same principle.If it seems it would help you for some reason go for it, I'll pass.Too much time invested at this point to risk damaging what it close to a finished pen.

Eagle, I'm not sure how doing it between dead and live centers would flare the barrel if we are using pen kits where the bushing holds the barrel. The brass barrell never touches a center in what we're talkin about--- the centers will hold the bushings, the bushings hold the blank. Ie, everything but a non-7mm blank. The only pressure on the blank will be lateral pressure-- and if you apply enough lateral pressure to goof the blank, ya deserve to mess it up [8D]. We spoke on the phone a while back about roughing blanks between a dead and live center (without bushings) but you warned me not to do that, and I haven't.

On the home page there is an aricle about making bushings out of Corian.That would seem like it is the opposite end of the spectrum.I'll stay in the middle with what I can buy with the kits.(I have made bushings out of brass and plastic bread board stuff.Some use Delrin.It doesn't seem there is a need for harder bushing otherwise the Mfgr's would have already done it and priced them accordingly[]

I thought they used the plastic bushings for lacquer dipping? I read the tutorial and they didn't mention it but I was understanding it to be bushings for finishing. Are people actually using plastic bushings for turning?

 

[wdcav1952]

Matt, I agree with the last part of your post. I thought that the alternative material bushings were for finishing and dipping.

 

[ctEaglesc]

"Eagle, I'm not sure how doing it between dead and live centers would flare the barrel if we are using pen kits where the bushing holds the barrel. The brass barrell never touches a center in what we're talkin about--- the centers will hold the bushings, the bushings hold the blank. Ie, everything but a non-7mm blank. The only pressure on the blank will be lateral pressure-- and if you apply enough lateral pressure to goof the blank, ya deserve to mess it up . We spoke on the phone a while back about roughing blanks between a dead and live center (without bushings) but you warned me not to do that, and I haven't.
"

Maybe I missed the part about using the bushings or read it and misunderstood.Now the comment about the slimlines makes sense.
With my luck if they are not together on the mandrel I would lose them or assemble them backwards.
Not sure I'll try it(unless I need to) but thanks for clearing that up.
As far as using corian bushings for turning, from experience corian for me at least is a CA magnet.
Not using that for bushing material for sure.