Ok, this is getting annoying. What am I doing wrong?

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Painfullyslow

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Mar 5, 2022
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378
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This is my 5th failed attempt in a row at this type of blank. This is the same "V" type segmenting that I had done on other pens successfully but with aluminum instead of brass.

The failure always occurs at the metal bond on both the wood and acrylic side. This particular blank was done with T88 but other failures were attempted with thick CA (more as an experiment, I expected failure), Loctite 5 minute epoxy, JB Weld 5 minute epoxy, and two with T88. All have failed.

I have tried bonding an external brace to all four sides of the piece which only accomplishes holding it together until the brace is removed, at which point it falls apart.

My drill press is terrible. I can *feel* it cavitating when drilling but I am not convinced that this is the sole reason for failure as I managed to make the aluminum segments without issue.

Here is my process:

  1. Make the required cuts on the bandsaw
  2. all mating surfaces are scuffed with 120 grit sandpaper then cleaned with rubbing alcohol
  3. Epoxy is applied and the blank is assembled on a jig lined with wax paper. Nothing more than an L shape so that I have two flat 90 degree surfaces to secure against although with the blank above, it really isn't needed as the double V design is self-centering.
  4. Clamp the piece together from end to end. On this type of blank I do not clamp the piece to the jig at all, I merely use it as a stable platform while clamping the ends.
  5. Wait 24+ hours even if the cure time is shorter.
  6. Bond external bracing using thick CA. I usually use tongue depressors cut to size but will me moving to 1" L molding when I can get down to the local home depot.
  7. Put in the pen vise and take to the drill press
  8. Using a centering bit, I make the initial cut into the blank
  9. Switching to the correct diameter bit and begin cutting.
  10. Using a pecking method, keeping the bit cool so that it is only warm to the touch.
  11. When I get to the metal layer, I apply constant pressure for about 5 seconds then withdraw and wait about 30 seconds for the bit to cool down, then repeat.
It is somewhere in that last step where I feel the inevitable 'crunch' of the blank failure.

Is there some glaring error that I am missing?
I am wondering if I am squeezing out too much of the epoxy by clamping it? However if I skip this step I worry that the gaps between segments look sloppy.

I have taken to pre-drilling my 90 degree segments but something like this I do not see a way how it can be pre-drilled. Is that correct?

I would appreciate any advice on this, it is really becoming frustrating.
 
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I'm not a expert on this type of blank making, but what i see is different materials that conduct heat in a different way, so the heatexpansion is different for each material. Sometimes i use aluminum and pvc (both thin materials, 0.25 mm thick) in my pens and glue with thick CA.
I can imagine that if all matrials are thicker the heatexpansion rate could be a issue. In that case i would drill as slow as possible with freshly sharpened drillbits. Maybe you can drill on the lathe slower. I sharpen my drillbits freehand on the discsander and try on scrapwood if they are ok first. Hope this helps, good luck!!
 
You're heating up the glue while drilling. Slow it down, and if necessary use water to cool the drill bit one in awhile. I used a wet paper towel to wrap around the the bit. Turn the drill press off first😆 The heat melts the glue which causes separation at the joints.
 
Can't think of a way to keep it from separating without being there to watch your work; however, can't you clean it off and glue it as it is back with epoxy and clamp it as it hardens, and then after 24 hours re-drill to clean out the inside.

Not sure how you have done it time wise, but in the past some others and I myself have spent 24 to 48 hours drilling out snake wood to prevent it from heating to prevent it from cracking. That means drilling about 1/4" at a time and resting an hour or so. And the 1/4" is drilled over a 5 to 10 minute period. No, absolutely NO heat build up - was the point.
 
One other thing: For quite a few people, they try twice or three times and give up. Then a few others keep trying and keep trying until finally one works fine. Maybe two or three more failures and then two or three good ones, and then consistency in creating those blanks. This is more or less from 3 components - technique and experience plus skill development. The difference between failure and success is a minuscule leveling up of skill and technique gained through experience.

KEEP AT IT! 🙂👍
 
Although I don't do it, you could perhaps try using a smaller pilot drill to get through the metal first. As others have already stated - make sure you have a very sharp bit. - Good Luck, Dave
 
Melat lathe with a indexer and a live cutter on the tool post.
Or a mill
Walk in the park
 
Sorry, should have specified that I am using jobber bits that were just sharpened.

I have no intention of giving up. Now it is a matter of pride, I WILL make this blank work! :mad:

I may however hold off until I have a lathe that I can drill on. The way things are going I may just go and pick one up in the next day or two.
 
No one has mentioned wrapping your blank in gauze and soaking it in CA - it acts to hold the blank together. Also, I agree to slowing down the drill speed. I usually drill around 250rpm, which has worked for me. I drill on my lathe.
 
I may however hold off until I have a lathe that I can drill on. The way things are going I may just go and pick one up in the next day or two.

You don't have a lathe? Don't you turn pens?

When drilling is the blank held absolutely still ?

Is there slop in the drill press? If so it might be applying pressure on the way up.
 
All of the above applies. My contribution is to score the mating surfaces to help with some tooth. You can also do the popcilce stick trick that gets mentioned alot here in aiding the drilling part.
 
KMCloonan said:
No one has mentioned wrapping your blank in gauze and soaking it in CA - it acts to hold the blank together. Also, I agree to slowing down the drill speed. I usually drill around 250rpm, which has worked for me. I drill on my lathe.
Click to expand...
I don't use gauze, I use wood. It is glued to all 4 faces of the blank before drilling. I drill at the slowest speed my crappy drill goes to. I think 380rpm or thereabouts.


wouldentu2? said:
I may however hold off until I have a lathe that I can drill on. The way things are going I may just go and pick one up in the next day or two.

You don't have a lathe? Don't you turn pens?

When drilling is the blank held absolutely still ?

Is there slop in the drill press? If so it might be applying pressure on the way up.
Click to expand...

I just started this about two months ago and so I am using a little Penpal lathe. It turns ok but no actual chuck. I know they make a kit to allow for drilling on this unit but rather than spend $100 on that I would much rather just pick up a MIDI.

Yes, the blank is held still in a pen blank vise which is secured to the platform on the drill press
Yes, there is also slop in the drill press. Overall since I just started this most of the equipment that I am using is sub-par by most of your standards. Another reason for wanting to pick up a quality MIDI lathe.

jttheclockman said:
All of the above applies. My contribution is to score the mating surfaces to help with some tooth. You can also do the popcilce stick trick that gets mentioned alot here in aiding the drilling part.
Click to expand...
All mating surfaces are scored with 120 grit sandpaper. Do I need to do something other than this?

And I do the popsicle trick, except that I use larger size (tongue depressor size) for more surface contact.
 
Step drilling, combined with other methods to control heat buildup in your material can be a very effective way to manage the inevitable heat buildup when drilling.
 
Painfullyslow said:
I don't use gauze, I use wood. It is glued to all 4 faces of the blank before drilling. I drill at the slowest speed my crappy drill goes to. I think 380rpm or thereabouts.




I just started this about two months ago and so I am using a little Penpal lathe. It turns ok but no actual chuck. I know they make a kit to allow for drilling on this unit but rather than spend $100 on that I would much rather just pick up a MIDI.

Yes, the blank is held still in a pen blank vise which is secured to the platform on the drill press
Yes, there is also slop in the drill press. Overall since I just started this most of the equipment that I am using is sub-par by most of your standards. Another reason for wanting to pick up a quality MIDI lathe.


All mating surfaces are scored with 120 grit sandpaper. Do I need to do something other than this?

And I do the popsicle trick, except that I use larger size (tongue depressor size) for more surface contact.
Click to expand...
I always use an exacto knife to score scratches in an X pattern on both surfaces. Not sure if this will help but it can not hurt. If I use sandpaper I always use 60 grit. Anything more than that will not leave deep enough grooves.
 
SteveG said:
Step drilling, combined with other methods to control heat buildup in your material can be a very effective way to manage the inevitable heat buildup when drilling.
Click to expand...

I tried step drilling but did not have much success. Perhaps I will revisit it once I refine the rest of my technique.

jttheclockman said:
I always use an exacto knife to score scratches in an X pattern on both surfaces. Not sure if this will help but it can not hurt. If I use sandpaper I always use 60 grit. Anything more than that will not leave deep enough grooves.
Click to expand...
I will try that. It could be that my scratches simply aren't deep enough
 
Perhaps try drilling a hole in the brass sheet before building it into the blank?

I'm doing a thought experiment: imagine yourself as a drill bit, cutting through wood and suddenly you meet a piece of hard metal with a bend in it. If coming in from "the top of the V" not a big problem - perhaps a little skid to the bottom of the valley before drilling through the brass sheet. But if you meet the V from the sharp end, wouldn't there be a big temptation to skid sideways and follow the slope? (Test this by trying to drill a piece of bent brass sheet with no wood on top of it.)

Although, re-thinking that "coming in from the top of the V" - the angle of the bend in the metal sheet looks to be steeper than the grind angle of the drill bit. Meaning the wings of the bit are going to cut before the tip of the bit gets to the brass. I have no idea what that's going to do in terms of deflecting the tip of the bit - perhaps try that as well with the top exposed so you can see what happens.
 
rherrell said:
Don't use rubbing alcohol, it's mostly water. Acetone is your best bet for cleaning metal.
Click to expand...
Hmm, that is a fine point and something I hadn't considered. I just use RA because it is handy. Now I am wondering if the brass sheets come with some sort of coating to prevent tarnishing since this process worked with the aluminum. I will switch to acetone and give it a try.


duncsuss said:
Perhaps try drilling a hole in the brass sheet before building it into the blank?

I'm doing a thought experiment: imagine yourself as a drill bit, cutting through wood and suddenly you meet a piece of hard metal with a bend in it. If coming in from "the top of the V" not a big problem - perhaps a little skid to the bottom of the valley before drilling through the brass sheet. But if you meet the V from the sharp end, wouldn't there be a big temptation to skid sideways and follow the slope? (Test this by trying to drill a piece of bent brass sheet with no wood on top of it.)

Although, re-thinking that "coming in from the top of the V" - the angle of the bend in the metal sheet looks to be steeper than the grind angle of the drill bit. Meaning the wings of the bit are going to cut before the tip of the bit gets to the brass. I have no idea what that's going to do in terms of deflecting the tip of the bit - perhaps try that as well with the top exposed so you can see what happens.
Click to expand...

I had thought of this and with my junky drill press, deflection is absolutely a concern however I specifically designed these blanks so that the bit is come in from the top of the V so that it is funneled towards center. By the time it gets to the second V (coming in from the bottom) it is over an inch into the blank so it should have all of that surrounding tube to help stabilize the bit. It could be that it simply isn't enough.
 
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