Fusion blank turning issues?

[Atabuoy]

Admittedly still a rookie, having turned only 50 or so pens, I've stumbled on to fusion blanks. Absolutely love the finished product. My challenge is I have blown out at least 3 of the 6-7 I've tried. In fact the last one literally ripped out a section of the brass tubing along with the blank at about 85% complete.
Besides the frustration, these are relatively expensive blanks. I'm using an easy wood CI R2 chisel (newly sharpened) and have been experimenting between 1500-2000 rpm. My cuts have been excruciatingly light. Never in a hurry. At the first sign of trouble I patch with CA glue/activator. I also use a mandrel saver if that makes any difference? Appreciate any thoughts or ideas others might have. Thank you.

 

[jttheclockman]

https://www.woodturnerscatalog.com/docs/fusion_blanks.pdf

 

[wood-of-1kind]

If using carbide tooling I turn at highest rpm (3500) but without forcing the tool. Let-the carbide do the work. It's been my
experience that carbide likes "speed" and running at lower speed does not help much.

 

[egnald]

That really stinks. Pictures to the forum might be very helpful along with an explanation of the glue and process you used for drilling and gluing in the blank. My first inclination would be inadequate glue coverage between the tube and the blank.

You will likely get many answers to your question. I don't have a perfect system, but I can tell you what I do and what I've learned about how important good glue coverage is to prevent catches from tearing your blank apart (as you have already found out the hard way).

I clean the inside of my blanks after drilling and before applying glue. I use a small brush on a wire (designed to clean re-usable straws) and compressed air to clean them so there is no powdery residue that can interfere with glue adhesion. On some wood blanks depending on how oily they are, like Olive and Cocobolo, I also use a swab and Denatured Alcohol and compressed air to clean out any surface oils before gluing in the tubes. I don't know whether it would help with fusion blanks, but I don't think it would hurt either.

I use epoxy to glue my tubes in and then use CA to fill in any gaps that show up.
First, I use something called "foundation wax" to plug the ends of my tubes to help keep glue out of them when I am inserting them into the blanks. I think other people use Play-Dough, or Base Plate Wax (like Ed sells on Exotic Blanks).

After the epoxy has set for an hour or so, I use my belt sander to square the blanks to the tubes. At that point, if there is a visible gap between the blank and the tube, I use a technique I learned from Zac Higgins to where I plug the end of the tube with a silicone stopper and then flood thin CA glue into the gap. Zac has a video that explains it far better than I ever could. Here is the the link to his video is How I Glue Tubes in Acrylic and Mixed Material Pen Blanks.

Another great video about why good gluing technique is so important was done by Mark Dryer. I think both of these are worth taking a look at. Here is a link to Mark's video: 10 Minutes To Better Pen Making - Gluing - Mark Dreyer.
In any case, here is the process I use in case it helps:

Best Regards,
Dave

 

[leehljp]

In the link that John T posted, it mentions a scraper with a negative bevel. That makes cutting less aggressive. IF you use a carbide insert tool, there are round negative bevel carbide inserts available for order.

Thank you John T for the link. I enjoyed reading it.

EDIT: Just re-read your post. You do use a carbide insert tool. Look for and order a negative bevel insert and give that a try.

 

[Atabuoy]

That really stinks. Pictures to the forum might be very helpful along with an explanation of the glue and process you used for drilling and gluing in the blank. My first inclination would be inadequate glue coverage between the tube and the blank.

You will likely get many answers to your question. I don't have a perfect system, but I can tell you what I do and what I've learned about how important good glue coverage is to prevent catches from tearing your blank apart (as you have already found out the hard way).

I clean the inside of my blanks after drilling and before applying glue. I use a small brush on a wire (designed to clean re-usable straws) and compressed air to clean them so there is no powdery residue that can interfere with glue adhesion. On some wood blanks depending on how oily they are, like Olive and Cocobolo, I also use a swab and Denatured Alcohol and compressed air to clean out any surface oils before gluing in the tubes. I don't know whether it would help with fusion blanks, but I don't think it would hurt either.

I use epoxy to glue my tubes in and then use CA to fill in any gaps that show up.
First, I use something called "foundation wax" to plug the ends of my tubes to help keep glue out of them when I am inserting them into the blanks. I think other people use Play-Dough, or Base Plate Wax (like Ed sells on Exotic Blanks).

After the epoxy has set for an hour or so, I use my belt sander to square the blanks to the tubes. At that point, if there is a visible gap between the blank and the tube, I use a technique I learned from Zac Higgins to where I plug the end of the tube with a silicone stopper and then flood thin CA glue into the gap. Zac has a video that explains it far better than I ever could. Here is the the link to his video is How I Glue Tubes in Acrylic and Mixed Material Pen Blanks.

Another great video about why good gluing technique is so important was done by Mark Dryer. I think both of these are worth taking a look at. Here is a link to Mark's video: 10 Minutes To Better Pen Making - Gluing - Mark Dreyer.
In any case, here is the process I use in case it helps:

Best Regards,
Dave

 

[Atabuoy]

Appreciate you sharing your detailed process Dave.
About the only appreciable difference in my process is that I don't specifically clean out the blank prior to inserting glued tube. A noteworthy improvement opportunity, thank you. I use epoxy on tubes that have been coarsely scoured with 60-80g. I also make an effort to spin, rotate, push, pull the tube into the blank to maximize coverage and dab additional epoxy on the ends which almost form a small donut at the ends which are plugged with dental wax. I let them cure overnight. I flush up the ends in my drill press with a barrel trimmer. No gaps.
And I can't emphasize enough how slow and light my cuts are. I'm soooo careful, and my cutters are super sharp. And as mentioned, if I feel the slightest tick, I stop, inspect and patch with CA glue to preempt trouble.
I've attached a couple of pics. One pic shows 2 separate examples of blow outs on 2 similar but different blanks. Note that one actually has a piece of the tubing ripped out. Kinda tells me there's good glue coverage/adhesion, at least on that one? The other pic shows 2 completed fusion pens that confirm it can be done! And the results of success just make the failures more frustrating.
Someone mentioned "negative rake" cutters, never used one?

thanks,
AB

 

[Atabuoy]

In the link that John T posted, it mentions a scraper with a negative bevel. That makes cutting less aggressive. IF you use a carbide insert tool, there are round negative bevel carbide inserts available for order.

Thank you John T for the link. I enjoyed reading it.

EDIT: Just re-read your post. You do use a carbide insert tool. Look for and order a negative bevel insert and give that a try.

Good advice all!
And particularly as you did, I enjoyed link John T posted. Very informative.
definitely interested in pursuing the whole negative rake approach. Becoming quite clear that fusion blanks need a different approach.
thank you,
AB

 

[bugradx2]

Appreciate you sharing your detailed process Dave.
About the only appreciable difference in my process is that I don't specifically clean out the blank prior to inserting glued tube. A noteworthy improvement opportunity, thank you. I use epoxy on tubes that have been coarsely scoured with 60-80g. I also make an effort to spin, rotate, push, pull the tube into the blank to maximize coverage and dab additional epoxy on the ends which almost form a small donut at the ends which are plugged with dental wax. I let them cure overnight. I flush up the ends in my drill press with a barrel trimmer. No gaps.
And I can't emphasize enough how slow and light my cuts are. I'm soooo careful, and my cutters are super sharp. And as mentioned, if I feel the slightest tick, I stop, inspect and patch with CA glue to preempt trouble.
I've attached a couple of pics. One pic shows 2 separate examples of blow outs on 2 similar but different blanks. Note that one actually has a piece of the tubing ripped out. Kinda tells me there's good glue coverage/adhesion, at least on that one? The other pic shows 2 completed fusion pens that confirm it can be done! And the results of success just make the failures more frustrating.
Someone mentioned "negative rake" cutters, never used one?

thanks,
AB

well at the very least the completed pens are beautiful.

Are you seeing the blank fracture immediately when you start turning or after a while? I am about to start my first inlay pen and had two people suggest sanding before any turning to make sure everything is at the same height to reduce the odds of a catch. It sounds like these are breaking half way down for you though

 

[Atabuoy]

well at the very least the completed pens are beautiful.

Are you seeing the blank fracture immediately when you start turning or after a while? I am about to start my first inlay pen and had two people suggest sanding before any turning to make sure everything is at the same height to reduce the odds of a catch. It sounds like these are breaking half way down for you though

Appreciate the compliment!
As I mentioned, achieving a successful result with one of these unique blanks just makes failure that much more frustrating.
As you can see from my pics, I've been on the home stretch turning both of these blanks. Everything was quite smooth, with no indication of gaps or imperfections, until disaster struck. My experience to date has taught me to expect gaps or imperfections and as such, I have caught them early, patched with CA glue and moved on. But I need to do better.
I'm a firm believer in the basic concept, "if you don't do anything different, why would you expect a different result?"
After reading some of the comments here and further research, my next step will be to use a negative rake carbide cutter. It's already been ordered. Wish me luck and good luck to you as well.

 

[bugradx2]

Appreciate the compliment!
As I mentioned, achieving a successful result with one of these unique blanks just makes failure that much more frustrating.
As you can see from my pics, I've been on the home stretch turning both of these blanks. Everything was quite smooth, with no indication of gaps or imperfections, until disaster struck. My experience to date has taught me to expect gaps or imperfections and as such, I have caught them early, patched with CA glue and moved on. But I need to do better.
I'm a firm believer in the basic concept, "if you don't do anything different, why would you expect a different result?"
After reading some of the comments here and further research, my next step will be to use a negative rake carbide cutter. It's already been ordered. Wish me luck and good luck to you as well.

Anytime, they're quite striking pens

Can you please update the thread with what happens when you turn with the negative rake cutter? I have some hybrid stuff that I intend to turn sometime hear in the next 4-6 weeks and would love to know if it works better for you.

 

[greenacres2]

In your first post, you mention carbide inserts that are "freshly sharpened". Are you trying to sharpen carbide yourself, and if so what techniques do you use? Or were you meaning that you've freshly rotated to a new edge? I'm wondering if your tool is as sharp as you think it is. (dull ones still cut skin pretty easy!!) I'm mostly steel tools for everything but pens, where i use carbide. That said, i tend to rough with a carbide tool that is "reasonably sharp" to me, and a separate tool to finish to keep that factory edge fresh as long as possible.
Another possibility is that light cuts still generate heat, and if done over several minutes the heat build-up may contribute to separation. If that's the case, solution is to take a cooling break!!
Your finished pens are beautiful, so don't stop!!

 

[darrin1200]

Appreciate you sharing your detailed process Dave.
About the only appreciable difference in my process is that I don't specifically clean out the blank prior to inserting glued tube. A noteworthy improvement opportunity, thank you. I use epoxy on tubes that have been coarsely scoured with 60-80g. I also make an effort to spin, rotate, push, pull the tube into the blank to maximize coverage and dab additional epoxy on the ends which almost form a small donut at the ends which are plugged with dental wax. I let them cure overnight. I flush up the ends in my drill press with a barrel trimmer. No gaps.
And I can't emphasize enough how slow and light my cuts are. I'm soooo careful, and my cutters are super sharp. And as mentioned, if I feel the slightest tick, I stop, inspect and patch with CA glue to preempt trouble.
I've attached a couple of pics. One pic shows 2 separate examples of blow outs on 2 similar but different blanks. Note that one actually has a piece of the tubing ripped out. Kinda tells me there's good glue coverage/adhesion, at least on that one? The other pic shows 2 completed fusion pens that confirm it can be done! And the results of success just make the failures more frustrating.
Someone mentioned "negative rake" cutters, never used one?

thanks,
AB

The only way I can see the brass getting ripped out, is if it was thinned to the point of failure. Enough force to tear out a piece of solid brass tube, would cause a lot more damage to the blank than that.
Two thoughts that come to me.

How do you score the exterior of the tube? A couple of strokes by hand with course grit, or by quickly passing across a sanding belt or disc.
If the latter, that could explain the pieces popping off. I have personally found that a lot of care is needed to drill through dissimilar materials, as it can cause irregular shaped holes, which can cause voids that become weak glue joints. This combined with excess sanding, even a minor amount, would drastically increase the chance of bond failure.

For the hole that tore. Do you use a barrel trimmer that has the cutting edge along barrel for cleaning glue out? If so, is it exactly the correct size? If it's even slightly smaller, it could have some side play allowing the glue cleaning edge to contact the wall of the tube and actually remove material. This in combination with sanding could cause an extremely thin spot, or actual hole, to be created in the tube wall.

Just a couple of thoughts on possible causes.

 

[Atabuoy]

The only way I can see the brass getting ripped out, is if it was thinned to the point of failure. Enough force to tear out a piece of solid brass tube, would cause a lot more damage to the blank than that.
Two thoughts that come to me.

How do you score the exterior of the tube? A couple of strokes by hand with course grit, or by quickly passing across a sanding belt or disc.
If the latter, that could explain the pieces popping off. I have personally found that a lot of care is needed to drill through dissimilar materials, as it can cause irregular shaped holes, which can cause voids that become weak glue joints. This combined with excess sanding, even a minor amount, would drastically increase the chance of bond failure.

For the hole that tore. Do you use a barrel trimmer that has the cutting edge along barrel for cleaning glue out? If so, is it exactly the correct size? If it's even slightly smaller, it could have some side play allowing the glue cleaning edge to contact the wall of the tube and actually remove material. This in combination with sanding could cause an extremely thin spot, or actual hole, to be created in the tube wall.

Just a couple of thoughts on possible causes.

Appreciate your thoughts/comments.
As to your questions, I score using 60-80 grit and only enough to score to improve adhesion. Second, I do use a barrel trimmer. My kit has precise sizes for specific tube sizes. The core bits do have sharpened flutes that clear and residual wax or adhesive.

As mentioned previously, I've ordered a negative rake carbide cutter which I will be using on my next fusion project.
I'll let this group know how I do......

btw, nice to get lots of comments. Provides both new ideas and a review of what you have been doing.

 

[Atabuoy]

In your first post, you mention carbide inserts that are "freshly sharpened". Are you trying to sharpen carbide yourself, and if so what techniques do you use? Or were you meaning that you've freshly rotated to a new edge? I'm wondering if your tool is as sharp as you think it is. (dull ones still cut skin pretty easy!!) I'm mostly steel tools for everything but pens, where i use carbide. That said, i tend to rough with a carbide tool that is "reasonably sharp" to me, and a separate tool to finish to keep that factory edge fresh as long as possible.
Another possibility is that light cuts still generate heat, and if done over several minutes the heat build-up may contribute to separation. If that's the case, solution is to take a cooling break!!
Your finished pens are beautiful, so don't stop!!

Thanks.
As for "freshly sharpened", I've done both, 1/4 turn to new face and I have also sharpened my carbide cutters using 400 and 1000 grit plates with mineral oil. While self sharpening may not be as good as brand new, I would put it at about 75%+, certainly based on cutting results.
I do agree that light cuts generate heat....quite a bit! You can feel it while lightly guiding the steel square stock along the tool rest.
My negative rake cutter has arrived, just waiting for new fusion blank order to get here. Anxious to incorporate all the ideas and recommendations provided from this group.

 

[Atabuoy]

Admittedly still a rookie, having turned only 50 or so pens, I've stumbled on to fusion blanks. Absolutely love the finished product. My challenge is I have blown out at least 3 of the 6-7 I've tried. In fact the last one literally ripped out a section of the brass tubing along with the blank at about 85% complete.
Besides the frustration, these are relatively expensive blanks. I'm using an easy wood CI R2 chisel (newly sharpened) and have been experimenting between 1500-2000 rpm. My cuts have been excruciatingly light. Never in a hurry. At the first sign of trouble I patch with CA glue/activator. I also use a mandrel saver if that makes any difference? Appreciate any thoughts or ideas others might have. Thank you.

UPDATE:
First off want to thank everyone for their comments. It really does help.
For what it's worth, I went the negative rake route. I also used CA glue to secure brass tube.
I initially started with standard CiR2 for roughing from square blank to round. My thinking was to preserve new NR cutter till it was needed. Have to say the NR experience was quite anticlimactic in that it worked effortlessly and smoothly. Also noted it generated less heat? To be fair, this pen is a single barrel, larger diameter model but nonetheless, I'm pleased with the results. Looking forward to doing more fusion blanks.

 

[bugradx2]

UPDATE:
First off want to thank everyone for their comments. It really does help.
For what it's worth, I went the negative rake route. I also used CA glue to secure brass tube.
I initially started with standard CiR2 for roughing from square blank to round. My thinking was to preserve new NR cutter till it was needed. Have to say the NR experience was quite anticlimactic in that it worked effortlessly and smoothly. Also noted it generated less heat? To be fair, this pen is a single barrel, larger diameter model but nonetheless, I'm pleased with the results. Looking forward to doing more fusion blanks.

That looks great!

I've actually gone to the point of using my negative rake to turn everything with my acrylics from start to finish. I've noticed the same as you that they really do a nice job turning everything down.

 

[egnald]

On precious blanks I use a bandsaw jig to cut the corners off instead of turning them off. Some people even sand them down a little, anything to reduce the tool impact forces that are present until the blank is round and the tool forces become shearing and scraping instead.

I'm glad the Negative Rake worked out for you. Your hybrid pens are very cool.

Dave

 

[NGLJ]

I use negative rake 2R carbide cutters for pen turning, period! I have one turning tool that gets used 99% of the time. The downside of NR carbide is that re-sharpening can be very difficult to impossible compared to pure square cutters, which can be re-sharpened fairly easily. So, the choice is saving some money vs consistency/reliability of turning pretty much anything (NR cutters). Where have we heard that before? These days I don't even think about which cutter to use. I simply pick up my one "go to" tool and enjoy making pens! Since using NR carbide I have had virtually no blow-outs. On the rare occasion that it has happened it has always been a gluing issue, which was down to me. With a few exceptions where I use epoxy, I use polyurethane glue because it is gap filling and it really "sticks"! It is simpler to use than epoxy and sets fairly quickly. I rarely see it mentioned here but it works very consistently for me. The only thing to remember is that it needs moisture to cure. When not using wood, I simply wet the inside of the drilled blank before inserting the glue costed tube. You will know that it is working when you see foam.

 

[JohnU]

As mentioned above, polyurethane glue or 2 part epoxy to secure your tubes will definitely help reduce your chance of blowouts. CA glue is more brittle and doesn't have the strength or flexibility that the other two mentioned has for holding the tubes during turning. Saturating the wood part of the blank with ultra thin CA during turning will also help. It will wick in and stabilize the wood. You may have to apply it a few times during turning as you remove material but it helps.