PR Question

[RickW]

I just attempted to turn my first PR blank from the Prince with terrible results. I used a skew to turn it down as I always do but it was coming out terrible and I knew it was going to take a lot of sanding. I attempted to sand it out and I guess I got it too hot and both barrels cracked badly. I am definitely not blaming the PR, it was all my fault, but I need to know if a skew is the right tool or should I be turning with something else? Thanks for any help.

 

[DurocShark]

Skew is great, but takes a "LOT" of tool control to have nice straight sides on a PR blank.

I prefer the roughing gouge for most of the cutting and shaping, with a skew to give the final smooth cut.

 

[KenV]

Rick --

A skew works well, but the techniques for sharpening and use are different with plastics than for wood. There are several videos in the library from Ed Davidson (YO-Yo Spin) who is a master of turning for plastics. Note that Ed uses a skew with a much steeper sharpening angle. the length of the bevel is about the thickness of the skew. Ed also presents the skew into the plastics at more of a "scrape" presentation with the tool rest very close to the turning.

Sharp counts as does the depth of cut. I cannot take heavy cuts without the deadly bissing sound of plastics chipping out leaving pits.

 

[TomW]

I attempted to sand it out and I guess I got it too hot and both barrels cracked badly. I

I never dry sand anymore. Wet sanding with a water dropper bottle, finger for temperature sensor...

Tom

 

[ed4copies]

Rick,

Sorry to hear you are having difficulties.

For me, the skew is the correct tool. But, when I teach, I always try to stress that you may have a DIFFERENT right tool, for you. Most important, you need to develop a technique that removes material in "ribbons". This can be done with nearly any tool, after the blank is rounded. So, there is no RIGHT way, just YOUR way that works for you.

For many years, I turned resins with a gouge. After I learned the skew it was MUCH easier. Since then, I have also turned a couple with a scraper (just to learn how to do it). Do what makes YOU comfortable. The biggest cause of problems is our nerves, I believe.

Next time you order, send a PM to me and I will send you a group of "seconds" as your "freebees". You can practice turning these. IF they come out, they will be nice pens, but the mix is not optimal, so Dawn won't sell them.

BTW, this offer is OPEN to ALL!! TELL US, if you have not turned resins and we will include some to play with. Practice leads to confidence!!

As a member once used as a signature line, "Failure is just one step on the pathway to success!!"

Good Luck

 

[ldb2000]

I use ONLY the skew for turning plastics . It requires a very light touch to turn without chip out . Was this a PR blank or a Imported resin blank ? The PR blanks are more forgiving of heavy cuts , the imported resin blanks are very brittle and chip out very easily . If you hear what Ed Davidson the breaking glass sound , that is chip out happening , the resin is actually shattering and leaving a very rough surface .
As for sanding , some swear by wet sanding but I dry sand and have never had a blank crack from heat . Just how hot did you get the blank ?

 

[jkeithrussell]

Ed also presents the skew into the plastics at more of a "scrape" presentation with the tool rest very close to the turning.

This is important. I use a skew on PR after it is rounded with my Woodchuck, and I try to remember to keep the tool rest very nearly touching the blank. When I forget, the blank reminds me by giving me a lot of chatter. I use a short skew, choked up, with the rest as close as it will get, and it generally produces good results.

 

[ed4copies]

I use a skew at a near vertical angle (74.375 degrees, approximately)

Not that it matters, it just shows YOU can use any approach that works for YOU.

 

[RickW]

Thanks for all the inputs.

Ken, I have watch yoyospins videos and have actually downloaded them to my computer so I can go back to them. I even emailed Ed Davidson about his skew and he replied with pictures to show me the difference in his skew grind and a normal skew.

Butch, no it is the Midnight Blues PR.

I know it is me and my technique and I was looking for some pointers to help out and you guys came through as I knew you would.

Thanks for the help. I will just have to practice till I get it right.

 

[heinedan]

Rick,

I too had problems tuirning the PR. It is very different that the acrylic blanks from CSUSA or others. I found that when I used a gouge, it would chip out and eventually a large piec e would break off the blank. Thriugh a trial and error process, I have found that by taking the blank round with a roughing gouge, then switching to a skew with a lacer grind gives me flawless results. I found that a standard skew is to easy to catch on the corners of the skew.
Once again, this is what I found that works for me. Someone else may have a anpther process that works for them.

Good Luck,
Dan

 

[RickW]

Rick,

lacer grind

Good Luck,
Dan

What is a lacer grind?

Thanks

 

[Spats139]

With one exception, the only tool I use is a skew; the exception is a thin parting tool when I need to turn down to the tube for a center band.

Most of the time things go well, but when I do have problems I first try resharpening the tool; it may be getting dull, or I may have messed up the previous sharpening; and then, if resharpening doesn't make a difference, I just walk away for a bit. I find it's best to come back later, for a fresh start, because if I keep pressing on when things aren't working I know there's a good chance they'll just get worse.

I may have been getting impatient earlier, or I was unconsciously changing some small part of my technique, but things just weren't feeling right. Walking away and returning is sort of like hitting the reset button. In fact, I'm doing that right now with an Invisavue blank; I don't know why, but the red ones always give me more grief than any other colour, or any other blank for that matter!

Above all else, remember that this is supposed to be fun. So, when these little challenges pop up - pause; breathe; smile; and try again. Or, if that's not really in your nature, try swearing and kicking something; that also seems to be popular with some folks.

 

[mdburn_em]

Lacer grind comes from how Alan Lacer grinds his skew.
http://www.woodturnerscatalog.com/store/Turning_Tools___Signature_Tools___Alan_Lacer?Args=

I'm sure that nobody else does plastic like this. I use my forged gouge and rip it down to an appropriate amount just above the bushings. Yes, it's very pitted, but it's also very fast and I don't have to worry about plastic ribbons wrapping around my blank and having to be cut off so I can see what I'm doing. Did I mention it's fast?

Then I take my skew and clean up the pits. By the time that's done, I'm ready to start sanding.
I've also never had a blank crack from sanding heat. Melting the grit off the sandpaper, but never bothered the blank. Must be lucky.

Oh, Did I mention my technique is fast?

 

[mickr]

very sharp skew after getting round..then very very gentle presentation..it takes tons of patience, but is worth it..if you do it well, it requires very little sanding & yes WET sand

 

[ed4copies]

If it works for YOU!!

Lacer grind comes from how Alan Lacer grinds his skew.
http://www.woodturnerscatalog.com/store/Turning_Tools___Signature_Tools___Alan_Lacer?Args=

I'm sure that nobody else does plastic like this. I use my forged gouge and rip it down to an appropriate amount just above the bushings. Yes, it's very pitted, but it's also very fast and I don't have to worry about plastic ribbons wrapping around my blank and having to be cut off so I can see what I'm doing. Did I mention it's fast?

Then I take my skew and clean up the pits. By the time that's done, I'm ready to start sanding.
I've also never had a blank crack from sanding heat. Melting the grit off the sandpaper, but never bothered the blank. Must be lucky.

Oh, Did I mention my technique is fast?

I LOVE SPEED!!!!!

BUT, when you use this method, you are "breaking off" the material. Those pits are uncontrollable, and CAN go as deep as the tubes, creating cracks in the final pen. This is especially true of the more brittle materials.

Use any technique that works for YOU, but if you have a blank break, there's a pretty good chance it was caused by the "stress" of the initial breaking you encouraged.

When it works, it IS quick. When it doesn't, you will know before you have to finish the pen turning. So, in either event, you will turn LOTS of pens. Just be aware that there will be some loss.

FWIW

 

[DurocShark]

I did an experiment with a square blank last night. I used a 1/8" parting tool to get the blank round and close to final size.

With this Castin Craft resin, I got ribbons and only a little bit of chipout while rounding, none once round. It was amazingly fast too.

Because you dig in it's difficult to have a smooth shape when done, you still end up doing a lot of cleaning with skew or gouge, so the time savings are probably a wash. But it was pretty cool to touch the tool to the spinning blank and watch it just sink into the resin.

 

[JimMc7]

I LOVE SPEED!!!!!

BUT, when you use this method, you are "breaking off" the material. Those pits are uncontrollable, and CAN go as deep as the tubes, creating cracks in the final pen. This is especially true of the more brittle materials.

<snip>

+1 This very thing happened to me recently with a beautiful Golden Ruby PR blank. Looked absolutely beautiful except for the 1/4" crack near the end of the tube. I tried wet CA sanding and couldn't hide the crack. On the pen portion of a Baron so I couldn't hide it with a clip, either. Sickening for me to trash such a nice blank.

I've since switched to first clipping the corners on a disc sander and only a few light passes with a roughing gouge to get rid of the high spots. I finish from there with a sharp skew in a scraping cut (radius skew blade edge generally parallel to the blank, entering at blank center line or a bit below). Ribbons spin off and no catches or breaking glass noise since I converted. Probably does take about 5 more minutes but worth it to a hobbyist like me where $s for blanks are more important than pens/day. Another bonus is I now start sanding at 240 grit versus 80 grit before. I dry sand the 1st grit because it's easier for me to see the surface is uniform and wet sand on subsequent grits (wiping the spinning blank with a wet Viva paper towel between grits).

 

[MHKogan]

What RPM are you turning the PR blank at? I find that speeding up the lathe to around 3,000 rpm works best for any type of resin blank. Also, knocking off the corners on a belt sander before turning on the lathe can reduce the stress on the blank and the lathe.

At the higher speed I start with a small gouge and take the blank down in smooth but shallow passes. Then I switch to the skew for final shaping and sizing.

 

[mdburn_em]

I LOVE SPEED!!!!!

BUT, when you use this method, you are "breaking off" the material. Those pits are uncontrollable, and CAN go as deep as the tubes, creating cracks in the final pen. This is especially true of the more brittle materials.

Use any technique that works for YOU, but if you have a blank break, there's a pretty good chance it was caused by the "stress" of the initial breaking you encouraged.

When it works, it IS quick. When it doesn't, you will know before you have to finish the pen turning. So, in either event, you will turn LOTS of pens. Just be aware that there will be some loss.

FWIW

I do realize the chances I'm taking. It's worked so far. Now watch, next time I go out to do a resin blank it will explode. Such is life.

I've wondered if I have better luck because of using the shallow forged gouge. Probably never know.

 

[ed4copies]

Confidentially, Mark, I used a similar approach for a long time. Worked very well on AA blanks. NOT bad on polyresin, then Dawn started introducing blanks that cost over $20 a piece and I changed my method. (Only had to mess up a couple to decide MY time was not THAT valuable.)

 

[mdburn_em]

Confidentially, Mark, I used a similar approach for a long time. Worked very well on AA blanks. NOT bad on polyresin, then Dawn started introducing blanks that cost over $20 a piece and I changed my method. (Only had to mess up a couple to decide MY time was not THAT valuable.)

I understand. The method I'm describing (and you're agreeing with) is for the $2-5 blanks.

It's a whole different story with something like the rattlesnake blanks. There is a whole lot of sanding with something like that. preliminary sanding with my belt sander (getting close to round), then using the skew and stopping well short of final size. Last step is a lot of more sanding to size.

 

[ed4copies]

I understand. The method I'm describing (and you're agreeing with) is for the $2-5 blanks.

It's a whole different story with something like the rattlesnake blanks. There is a whole lot of sanding with something like that. preliminary sanding with my belt sander (getting close to round), then using the skew and stopping well short of final size. Last step is a lot of more sanding to size.

Yep, we are on the same page.