Celtic knot disaster

[bloodhound]

Hello all. I have a question/problem.

I am making a celtic knot for a customer. I have made them before. And i have about a 60% success rate. This time it is to be maple and green acrylic. I was patient. I cut my blank at 45%. Glued in my inlay with 5 min epoxy. Next day, trimmed the excess. Wash and repeat. Took 4 days. Tonight i drilled and glued in the tube. Sanded the tube and glued with epoxy also. waited about an hour, and started turning. About the time i got it round. It let lose. I was taking lite cuts. I have seen/read people use wood glue and CA. And they didnt blow apart.

I will start over tomorrow. So any tips on what i may have done wrong would be great. My only idea is maybe my epoxy was old? Or maybe i just suck. That is always an option. lol.

Thank you ahead of time for your input.

Bill

 

[jttheclockman]

Unless you are using all wood on all aspects of the knot, never use wood glue . You can use Med CA or I prefer epoxy. Never use thin CA because it will get absorbed into the wood and will not make a good bond. You are using different materials and each turn differently because of the hardness factor is different with both. This is why you are having a little bit of a problem turning it.

As you said make sure the glue is fresh. Make sure the gaps are correct with the infill material. Being you got it to round you can skip the step with adding wood on the sides for drilling purposes. The epoxy for the tubes needs to set not only dry so leave sufficient time for this part.

As I said 2 different materials so be careful when turning. Both turn differently so a light touch is needed. I prefer a skew. Good luck.

One other little trick is to keep adding some thin CA to the blank as you turn it down. Helps hold things together.

 

[MTViper]

When you say "It let loose" do you mean the blank started turning on the tube or the blank came apart at the seams?

If it was the blank turning on the tube, my suggestion is to give the epoxy 24 hours to cure before you turn it. Makes a big difference over the 30 minutes it takes to set.

If it came apart at the seams, did you clamp the blank between each glue-up to make sure each joint was flush and set? That's where I'd check first.

 

[jmm666]

I have made several knots had this happen to me. I believe the problem is gluing. When a knot is being turned, there are tiny pieces within the knot that become exposed. These pieces are between the crossing lines. If any one of those is not really stuck to the tube, it will become airborne during turning. The parts of the knot must be thoroughly stuck to itself and to the tube. All I can suggest is to work on the gluing process to get complete coverage of the entire knot area and maybe add some thin CA as John suggested. That can help solidify the assembly from the top.

Good luck

 

[plantman]

I always use thick or gap filling CA to glue my segments together using an accelerator after each piece. After drilling I soak the inside and outside of the blank with thin CA and accelerator. This will seep into any cracks on the inside. Re-drill your inside hole to remove any excess glue. I also use thick/gap filling CA to glue my tubes into my blanks. This will fill any remaining voids and give you a little longer working time. Mount your blank and turn round. Stop the lathe and inspect your blank. Re coat with thin CA and accelerator to fill any voids that may appear. Repeat this every 3 or 4 cuts until you reach your desired size. Sand your blank and clean off any dust with a tac rag. I seal my blanks with 8 coats of thick CA, sand with 220 and 1200 until all shiny spots are removed, and polish. You problem may in the drilling process, as heat will soften most glues. I know this answer is more than you asked for being you are a more seasoned turner, but I thought some of the new people may get some segmenting and finishing tip answers out of it. Mine, by far, is not the only way, but is the way that suits me best for the outcome I want to achieve. Jim S

 

[bloodhound]

Nope not more than i asked for. I thank you all for you advice. i will head back out to the shed after i finish splitting fire wood. I will let you know how it works out. Thanks again.

 

[jfoh]

Celtic knots, like many segmented blanks, are in fact bombs waiting to explode. You can reduce the issue in a few ways. I find that after drilling the blank that a good soaking with thin CA down the new hole makes it much stronger. I re-drill the blank to make sure the tube fits easily. When turning I sometimes soak the blank with thin CA to make it stronger as I turn it. This fills in any minor voids in the glue up that are exposed as the blank is turned. Razor sharp tools and very light cuts help. But sometimes failure is the only outcome. I just try to make it a learning experience and try to learn what went wrong and how to avoid it.

 

[Displaced Canadian]

I'm also a fan of using thin ca as I turn anything segmented. Sharp tools are a must, go gently with a skew and remember that heat has a bad habit of causing glue to release.

Sent from my phone using some program.

 

[Joey-Nieves]

https://www.youtube.com/watch?v=Y9uQv5sKibk
I learned from this guy, All I want is the plans for his press

 

[dthayer]

All I want is his entire workshop!!!