Help in turning segmented blanks made up of small pieces

[Lew]

I need some advice on how to turn segmented pens. I have been trying my hand at segmenting and have been ok with pretty standard stuff--rings, knots, scallops and things of that sort (photo attached of one of these; forgive the quality of the photo)--but when it comes to building up a blank out of small pieces especially all wood, I have a problem in turning. Although use a sharp spindle roughing gouge and skew, I inevitably get large chunks that fly off, most times beyond my ability to patch them up.

So, I followed the advice of Roy Quast and George Valentine on this site and tried turning with just sandpaper, but I find that the end result is not really perfectly round but lopsided and I don't know how to correct that problem. The second photo shows how lopsided the blank is (the shiny stuff is epoxy with walnut sanding dust added to fill some gaps).

How do I go about turning something like this to get a decent result? Or is it just a matter of patience and learning? I really don't want to blow up dozens of blanks to get to the point where I know what I'm supposed to be doing. That's why I'm asking for help here. Thanks in advance for all the help.

 

[mark james]

Hi Lew, there can be many issues at play. Also more information would be helpful. But I'll offer a few comments; expect to get many more from others more experienced than me.

In the photo on the right, did you 'build' the blank on the tube, or construct it then drilled the tube hole?

In either case, the gap which you filled with epoxy will be problematic if you are using just sandpaper. The heat created will quickly soften the joint, as well as adhesion to the tube. I use epoxy all the time, so that is not the issue. Heat, inadequate glue coverage on the tube, possibly inadequate glue between the segments. Did the crack above show up after sanding down to size, or right from the assembly? I'd actually recommend going back to your tools.

And failures are a great learning tool... Take pictures, take notes, improve the process and tweak your skills. Keep asking questions!

The pen on the left is lovely.

 

[Beesville]

Lew, how are you assembling the blank? When making the cuts, what are you using? I prepare the blanks with TBII and let cure overnight. Then drill on the lathe for accuracy. I cut all segments on the table saw (lots of waste) then lightly sand. Segment pieces are then individually placed on the tube with thick CA between each and pressure applied. Depending on wood sometimes this CA presses through the pores when pressing down. I've never had any blowout on me with this process.

 

[Lew]

Hi Lew, there can be many issues at play. Also more information would be helpful. But I'll offer a few comments; expect to get many more from others more experienced than me.

In the photo on the right, did you 'build' the blank on the tube, or construct it then drilled the tube hole?

In either case, the gap which you filled with epoxy will be problematic if you are using just sandpaper. The heat created will quickly soften the joint, as well as adhesion to the tube. I use epoxy all the time, so that is not the issue. Heat, inadequate glue coverage on the tube, possibly inadequate glue between the segments. Did the crack above show up after sanding down to size, or right from the assembly? I'd actually recommend going back to your tools.

And failures are a great learning tool... Take pictures, take notes, improve the process and tweak your skills. Keep asking questions!

The pen on the left is lovely.

Hi Mark, thanks for the comments. I built the blank on the tube. I used another wooden blank with a partially drilled hole that to press down each piece as I assembled it to the blank using CA, but I still had one segment that had a sizable gap. I used expoxy with a drop of tint to fill that gap. The epoxy I have on the piece in the picture is because one of the walnut segments still had a chip even with sanding which as you say may be due to inadequate glue coverage. I'll try your suggestion about going back to the tools. And thanks for the compliment on the first pen.

 

[Lew]

Lew, how are you assembling the blank? When making the cuts, what are you using? I prepare the blanks with TBII and let cure overnight. Then drill on the lathe for accuracy. I cut all segments on the table saw (lots of waste) then lightly sand. Segment pieces are then individually placed on the tube with thick CA between each and pressure applied. Depending on wood sometimes this CA presses through the pores when pressing down. I've never had any blowout on me with this process.

Hi Jeffery, I tried drilling the blank after I had assembled the segments once before and had the blank blow up when I drilled so I thought I'd try to build the blank on the tube this time. I made the segments using TBIII (I know, overkill) letting each piece dry overnight before cutting and filling in with the second thin piece of walnut. (I forgot to mention, the wood is red oak and think walnut strips) I cut the blank using a thin kerf table saw blade and a sled I made for making pens. Then I used medium CA to assemble the segments on the tube having first added a sacrificial solid piece on the bottom to "hold" the segments in place. It sounds like I'm using the same process as you but most likely not making sure the segments are completely glued. I'll try the think CA and see if that makes a difference. Thanks

 

[Beesville]

Hi Jeffery, I tried drilling the blank after I had assembled the segments once before and had the blank blow up when I drilled so I thought I'd try to build the blank on the tube this time. I made the segments using TBIII (I know, overkill) letting each piece dry overnight before cutting and filling in with the second thin piece of walnut. (I forgot to mention, the wood is red oak and think walnut strips) I cut the blank using a thin kerf table saw blade and a sled I made for making pens. Then I used medium CA to assemble the segments on the tube having first added a sacrificial solid piece on the bottom to "hold" the segments in place. It sounds like I'm using the same process as you but most likely not making sure the segments are completely glued. I'll try the think CA and see if that makes a difference. Thanks

Sounds like the same process. I've used medium too but like thick more, it doesn't set up as fast. After glued together I put in clamps and wait 12-24 hours before pulling them out. I don't use a sacrificial piece, start with a flat surface and wax paper. Here's a finished pen. I'll try and find a pic or two of my process.

 

[Lew]

Sounds like the same process. I've used medium too but like thick more, it doesn't set up as fast. After glued together I put in clamps and wait 12-24 hours before pulling them out. I don't use a sacrificial piece, start with a flat surface and wax paper. Here's a finished pen. I'll try and find a pic or two of my process.

beautiful pen!!!

 

[jjjaworski]

Lew,

I noticed that the grain direction on the two wood species is different. The light open pore wood is side grain and the darker one seems to be end grain. This may be a contributing factor when your tool moves from one to the other was tool pressure grabs the side grain of the open pored wood.

I have had a few hiccups when I was turning some of those Radom segmented blanks because of the constantly changing grin directions in some of the sections of the blank. I blew a couple up in the learning process even using light cuts and a sharp tool.

Also, slow lathe speeds contribute to poor cutting action as well.

If I notice I have a difficult area on a blank as I turn it down , I try to fortify the wood fibers with some thin CA. Sometimes it works and sometimes it does not.

Good luck working through this. We learn so much from solving problems along the way.

The other pen is very nice. Good job on that.

Jim

 

[Lew]

Lew,

I noticed that the grain direction on the two wood species is different. The light open pore wood is side grain and the darker one seems to be end grain. This may be a contributing factor when your tool moves from one to the other was tool pressure grabs the side grain of the open pored wood.

I have had a few hiccups when I was turning some of those Radom segmented blanks because of the constantly changing grin directions in some of the sections of the blank. I blew a couple up in the learning process even using light cuts and a sharp tool.

Also, slow lathe speeds contribute to poor cutting action as well.

If I notice I have a difficult area on a blank as I turn it down , I try to fortify the wood fibers with some thin CA. Sometimes it works and sometimes it does not.

Good luck working through this. We learn so much from solving problems along the way.

The other pen is very nice. Good job on that.

Jim

Hi Jim, I see you are from one of my favorite places to visit. I don't think they are cross grained but I'll double check. If so, that could be part of my problem. I turn at about 2000 rpm, and try to make very light cuts. I'll try the thin CA routine as well. Thanks for the compliment on the other pen.

 

[KenB259]

It helps to flood the blank with thin CA, then apply accelerator, as you turn it down. I sometimes do this more than once on a blank. Be careful not to glue your bushings to the blank though.

 

[jttheclockman]

Hello Lew, your question is how to turn segmented blanks from what I got. Now from what is in that second photo is what we are talking about. There is some info missing but will run through a few things. First off your rings are not all the same size or they are too random unless that is the look you are going for. Never can tell what people are thinking. But lets start at cutting the rings. Are you cutting square and building the blank and then rounding or are you rounding the dowels and cutting rings?? Both methods can work but with each method there are things you need to be aware of. But whatever method you use the cuts need to be square or exactly the same diameters. After you cut you should take a piece of sandpaper and place on a flat surface. I like to use a piece of ceramic tile I bought at Home Depot. Some people use a piece of glass. What this does is clean the edges from fuzzies or saw marks which can keep the pieces from laying flat next to each other. If you use Titbond glue is fine. If you use med CA then what happens it gets absorbed real fast in end grain and a second coat is needed before you glue together. Trust me on this. I like to use epoxy because it gives me extra working time and I am also useing the tube so I am gluing the tube in at the same time. I use system3 t88 epoxy because it has a 24 hour cure time and plenty of open working time.

Next end to end grain is the weakest joint possible. Thus building on the tube will help eliminate extra stress from drilling. If you are building the blank with square pieces then knock off corners on a bandsaw or at a sander.

Now to your turning. Sharp tools as always important. Fast speed will help. Light touch especially when starting. Both those materials have different hardness values and you will cut faster into the walnut than the oak and your tool can dip in and catch the edges of the oak and chip either one of them. This is a matter of knowing how to control; your tools and not force them. If you are going to go the sand route then I highly suggest you use a back piece of wood under your sandpaper and not your fingers. I use a 1" X 2" wide strip of wood and wrap sandpaper around it. Move the sandpaper in circular motion as you are sanding and sand at slow speeds. You will need to stop the lathe and sand with the grain to get rid of sanding marks before you move up to next grid. If I have to sand wood blanks like this I will start with 220 grit if I need to get rid of alot of material bit normally will start with 400 and get to 800 before I start finishing with CA.

Hope some of this helps. good luck.

 

[Beesville]

beautiful pen!!!

Thanks

 

[Lew]

It helps to flood the blank with thin CA, then apply accelerator, as you turn it down. I sometimes do this more than once on a blank. Be careful not to glue your bushings to the blank though.

Thanks Ken. That makes a lot of sense

 

[Lew]

Hello Lew, your question is how to turn segmented blanks from what I got. Now from what is in that second photo is what we are talking about. There is some info missing but will run through a few things. First off your rings are not all the same size or they are too random unless that is the look you are going for. Never can tell what people are thinking. But lets start at cutting the rings. Are you cutting square and building the blank and then rounding or are you rounding the dowels and cutting rings?? Both methods can work but with each method there are things you need to be aware of. But whatever method you use the cuts need to be square or exactly the same diameters. After you cut you should take a piece of sandpaper and place on a flat surface. I like to use a piece of ceramic tile I bought at Home Depot. Some people use a piece of glass. What this does is clean the edges from fuzzies or saw marks which can keep the pieces from laying flat next to each other. If you use Titbond glue is fine. If you use med CA then what happens it gets absorbed real fast in end grain and a second coat is needed before you glue together. Trust me on this. I like to use epoxy because it gives me extra working time and I am also useing the tube so I am gluing the tube in at the same time. I use system3 t88 epoxy because it has a 24 hour cure time and plenty of open working time.

Next end to end grain is the weakest joint possible. Thus building on the tube will help eliminate extra stress from drilling. If you are building the blank with square pieces then knock off corners on a bandsaw or at a sander.

Now to your turning. Sharp tools as always important. Fast speed will help. Light touch especially when starting. Both those materials have different hardness values and you will cut faster into the walnut than the oak and your tool can dip in and catch the edges of the oak and chip either one of them. This is a matter of knowing how to control; your tools and not force them. If you are going to go the sand route then I highly suggest you use a back piece of wood under your sandpaper and not your fingers. I use a 1" X 2" wide strip of wood and wrap sandpaper around it. Move the sandpaper in circular motion as you are sanding and sand at slow speeds. You will need to stop the lathe and sand with the grain to get rid of sanding marks before you move up to next grid. If I have to sand wood blanks like this I will start with 220 grit if I need to get rid of alot of material bit normally will start with 400 and get to 800 before I start finishing with CA.

Hope some of this helps. good luck.

Thanks John for all the good input. I thought the rings were the same size except the solid walnut pieces are smaller intentionally. I'll double check my work on the other pieces from now on. I built this one on the tube using medium CA. I did not sand each piece which may explain a few of the gaps. I'll also try a slower setting epoxy instead of the CA because it sets so fast I can't handle it well. I built a jig to use on the bandsaw to cut off the edges of any square blank and that does help. Thanks again for the advice.

 

[leehljp]

Lathe Speed/ RPM: What seems to be missing, and I could have missed it is your lathe speed. What speed are you turning?
2500 at least but - 3000 - 3500 if possible, coupled with razor sharp tools and small bites.

 

[leehljp]

Need to add in this;
I have found that many people who turned bowls and even spindles tend to use slower speeds for pens, but pens require faster speeds because of their smaller diameters. And in general, using larger tools. Yes you can use the larger bowl tools and many people do. But it helps to have tools fitted to the pen - i.e. small skew, scraper or carbide inserts - and use light touches.

Plus, if you are using HSS, have the hone near by and swipe the tool across the hone a time or two every minute or so.

I just noticed that JohnT DID mention speed.

 

[TDahl]

Hi Lew,

Thank you for sharing this post, and thanks to everyone for sharing your knowledge. It is discussions like these that help everyone (especially us newbies) improve our skills.

 

[Lew]

Need to add in this;
I have found that many people who turned bowls and even spindles tend to use slower speeds for pens, but pens require faster speeds because of their smaller diameters. And in general, using larger tools. Yes you can use the larger bowl tools and many people do. But it helps to have tools fitted to the pen - i.e. small skew, scraper or carbide inserts - and use light touches.

Plus, if you are using HSS, have the hone near by and swipe the tool across the hone a time or two every minute or so.

I just noticed that JohnT DID mention speed.

Thanks Hank for the input. I had been turning at 2000, but I tried your suggestion last night to turn at 3000 (my machine goes up to 4700) and all went well. I'll try turning at these higher speeds, thanks.

 

[leehljp]

Thanks Hank for the input. I had been turning at 2000, but I tried your suggestion last night to turn at 3000 (my machine goes up to 4700) and all went well. I'll try turning at these higher speeds, thanks.

Glad it helps.

For some reason, the prevailing thought is often slower means less problems, catches and smoother controlled cuts, but it is not true as it concerns cutting. Faster causes less catches and chunks flying out.

 

[Lew]

Glad it helps.

For some reason, the prevailing thought is often slower means less problems, catches and smoother controlled cuts, but it is not true as it concerns cutting. Faster causes less catches and chunks flying out.

The only instruction I received on the lathe was from a class I took at a nearby Woodcraft store, and the instructor there said you should never turn over 800 rpm. That just didn't work for me so I started turning at higher speeds until I settled on 2000. 3000 and 3500 just seemed like overkill after his injunction about speed, but when I tried it last night, I was amazed at how smoothly I was able to turn the blank. I have learned more from the IAP site than anywhere else. Thanks again.

 

[leehljp]

The only instruction I received on the lathe was from a class I took at a nearby Woodcraft store, and the instructor there said you should never turn over 800 rpm. That just didn't work for me so I started turning at higher speeds until I settled on 2000. 3000 and 3500 just seemed like overkill after his injunction about speed, but when I tried it last night, I was amazed at how smoothly I was able to turn the blank. I have learned more from the IAP site than anywhere else. Thanks again.

800 RPM - that is what I figured. Most lathe classes, unless specific to pens or other very small diameter items, will tell the participants that there is a high end limit. 800 is the limit for 12 -13" diameter items. But pens require much faster RPM speed because of the smaller diameters.

Where instructors like that make errors is by not mentioning the technical aspect of "cutting speed", and instead use RPMs. 2500 rpm on a 3/4 " blank is slower Cutting speed than 800 rpm on a 12" bowl or platter.

 

[KenB259]

800 RPM - that is what I figured. Most lathe classes, unless specific to pens or other very small diameter items, will tell the participants that there is a high end limit. 800 is the limit for 12 -13" diameter items. But pens require much faster RPM speed because of the smaller diameters.

Where instructors like that make errors is by not mentioning the technical aspect of "cutting speed", and instead use RPMs. 2500 rpm on a 3/4 " blank is slower Cutting speed than 800 rpm on a 12" bowl or platter.

In addition, some chucks have a max speed as well.

 

[robutacion]

I need some advice on how to turn segmented pens. I have been trying my hand at segmenting and have been ok with pretty standard stuff--rings, knots, scallops and things of that sort (photo attached of one of these; forgive the quality of the photo)--but when it comes to building up a blank out of small pieces especially all wood, I have a problem in turning. Although use a sharp spindle roughing gouge and skew, I inevitably get large chunks that fly off, most times beyond my ability to patch them up.

So, I followed the advice of Roy Quast and George Valentine on this site and tried turning with just sandpaper, but I find that the end result is not really perfectly round but lopsided and I don't know how to correct that problem. The second photo shows how lopsided the blank is (the shiny stuff is epoxy with walnut sanding dust added to fill some gaps).

How do I go about turning something like this to get a decent result? Or is it just a matter of patience and learning? I really don't want to blow up dozens of blanks to get to the point where I know what I'm supposed to be doing. That's why I'm asking for help here. Thanks in advance for all the help.

G'day,

I see you mentioned my name and the system I normally suggest to deal with fragile and complicated segmentations when on the lathe, however, the results I see do not seem to have come from the "Flap Disc System" or FDS for short but rather from hand sanding while rotating on the lathe, that will certainly create undulations and unevenness on its roundness.

The 2 opposite centrifugal forces of both the lathe and FDS rotation leaves a surface as even as your hand can handle no different than holding the gouge steady on the banjo as it can also be used to support the grinder protecting disc cover for steadiness, I recommend and strongly advise the use of the 40 grit to start with and then the 100 grit to remove the previous grit marks, only then you can finish the surface by hand sanding.

The biggest mistake people make when using the FDS is to use very fine grits to cut large amounts of material, which not only become tedious, slow and creating excessive friction heat that on some solid woods blanks results in cracks and on segmented blanks the "melting" of the glue causing the blank to fall apart in more ways than one.

Was never a question of using the FDS to replace the gouges as was never a doubt that some people don't agree with it and that its fine too, like any systems we may use to do anything in life, practice makes a big difference and the FDS is no different, with a bit of practice you will be surprised as clean and fast you can turn a complicated or fragile blank from square to 95% done, successfully.

I just thought that I should "refresh" minds...!

Cheers
George

 

[Lew]

G'day,

I see you mentioned my name and the system I normally suggest to deal with fragile and complicated segmentations when on the lathe, however, the results I see do not seem to have come from the "Flap Disc System" or FDS for short but rather from hand sanding while rotating on the lathe, that will certainly create undulations and unevenness on its roundness.

The 2 opposite centrifugal forces of both the lathe and FDS rotation leaves a surface as even as your hand can handle no different than holding the gouge steady on the banjo as it can also be used to support the grinder protecting disc cover for steadiness, I recommend and strongly advise the use of the 40 grit to start with and then the 100 grit to remove the previous grit marks, only then you can finish the surface by hand sanding.

The biggest mistake people make when using the FDS is to use very fine grits to cut large amounts of material, which not only become tedious, slow and creating excessive friction heat that on some solid woods blanks results in cracks and on segmented blanks the "melting" of the glue causing the blank to fall apart in more ways than one.

Was never a question of using the FDS to replace the gouges as was never a doubt that some people don't agree with it and that its fine too, like any systems we may use to do anything in life, practice makes a big difference and the FDS is no different, with a bit of practice you will be surprised as clean and fast you can turn a complicated or fragile blank from square to 95% done, successfully.

I just thought that I should "refresh" minds...!

Cheers
George

Thanks George for the input. You're right, I did not use the FDS system but tried doing it with a block of wood and my hand. When I increased my lathe speed as others suggested, my tools did a fantastic job and I got no more tearout or chunks disappearing. I do intend to try your system with other projects to see how it works. As someone new to the whole process, I'm willing to try most anything to see what works best for me. Cheers.