Malachite Drilling Problems - Need Advice

[bcul01]

Guys,
I could use your advice. I just blew out two Malachite pen blanks while drilling out for a Statesman fountain pen.

I think my problem might have been that I had 3/4" x 3/4" blank when I probably need a 7/8" size.

But, I don't want to blow out a third. Any advice or unique things I should do to prevent blow out?

Thanks

 

[keandkafu]

Did you blow out the side or bottom? I have used the 3/4 for a majestic jr and was fine. Just make sure you are centered, the blank is true to the drill press and go sloow!

 

[Jim Burr]

JMHO, but those are best done a VS lathe...about 150 RPM. Never drill through, cut long drill just past tube depth and cut off the waste. Fast drill speed and trying to drill all the way through are the usual suspects.

 

[Ted iin Michigan]

Yes, they do suggest a 7/8" blank, but you should be able to do it. First, this Tru-stone can be an issue. My best results when drilling that large have been to pre drill a 7 or 8 mm pilot hole. Then follow up with the final size - but use a standard twist drill, not a brad point. Make sure the drills are sharp. And GO SLOW. Tru-stone gets soft when it overheats and hard, fast drilling will do just that. Pull out often and clear the flutes. And when you're about halfway, don't be afraid to pull out, shut down and take a few minutes for a granola bar (let's the blank and drill cool off). Then come back and finish up.

Some folk will even add a bit of cooling water to the hole but I've only had mixed success with that.

 

[rblakemore]

I have blown out malachite also

I like malachite also and have blown out.
I also have trouble when drilling with large diameter bits, sometimes acrylics get too hot and actually warp in the pen blank press. I will try 7 mm pilot holes also. Go slow and be patient. And I have slowed the drill press down; but, may slow more. Here is an Apollo Infinity in malachite that my wife made.

 

[thewishman]

#1 Don't use a brad point bit

#2 Cut blank a little long (3-4mm extra)

#3 Make sure bit is cleared and cooled

#4 Drill the last few millimeters advancing the bit slowly - very little pressure

A 3/4" blank works, I drill on the lathe. Good luck with the third blank.

 

[bcul01]

Malachite - Blew out the bottom

Did you blow out the side or bottom? I have used the 3/4 for a majestic jr and was fine. Just make sure you are centered, the blank is true to the drill press and go sloow!

Thanks. I am definitely going to slow down and I will double check the centering.

Bruce

 

[bcul01]

Malachite - Blew out the bottom

JMHO, but those are best done a VS lathe...about 150 RPM. Never drill through, cut long drill just past tube depth and cut off the waste. Fast drill speed and trying to drill all the way through are the usual suspects.

Yes...I did try to drill all the way through. Good idea to cut the blank long and cut off the waste.

thank you.

 

[bcul01]

Malachite - Blew out the bottom

I like malachite also and have blown out.
I also have trouble when drilling with large diameter bits, sometimes acrylics get too hot and actually warp in the pen blank press. I will try 7 mm pilot holes also. Go slow and be patient. And I have slowed the drill press down; but, may slow more. Here is an Apollo Infinity in malachite that my wife made.

Thanks for the advice.

Tomorrow, i am going to:

Adjust RPM slower
Start with smaller bit
Re-check centering of blank
Drill Slower
Drink a lemonade
Keep drilling slower
Not drill all the way through the bottom
Cut off waste

Great suggestions guys.

Note: Great looking Apollo Infinity pen that your wife turned! I can only hope mine turns out that nicely.

Bruce

 

[bcul01]

Thanks for the detailed input. I really appreciate it. This is for a customer's Father's Day gift and since this is my first stone to turn, I am on a fast learning curve.

By the way, been to Webberville several times for my son's high school athletic events.

Bruce

 

[raar25]

Also make sure you back off frequently and spray the bit with water every time you back off. This will help keep the temperature down.

 

[gbpens]

Sharpen the drill! Back up the material with scrap wood. Pull drill bit frequently to clear debris and cool bit with a damp rag. No need to dril farther than necessary. You may want to use the cutoff for a custom finial.

 

[Quality Pen]

I've recently been having good success on non-woods by keeping the bit cool with water. I go slow (IMO) especially compared to some videos on youtube that I've caught.

 

[randyrls]

Here is one additional tip(s). Mark the center of the blank. Drill from the center toward the end of the blank. Hold the brass tube against the drill bit. Mark the drill bit with a Sharpie marker. Drill into the blank until the mark disappears into the blank. You know you are deep enough.

 

[rblakemore]

I certainly agree with drilling Tru Stone slowly. I usually double check my drill centering by just pressing the drill on the blank for a second, than raising the bit to check the center hole is completely centered. In order to make my self slow down when drilling I slowly count to 5 when drilling, then withdraw the bit for another count of 5 and then repeat until I'm through. I also advance the drill slowly and remove the debris frequently. from the wife who made the malachite pen.

 

[Tom T]

If you are using a pen vice to hold the blank while drilling, make sure it is only snug, not tight. It will tend to crack the blank if it is to tight. Just my two cents. Every one else has good sense with the rest if there suggestions.

 

[bcul01]

Update. Turned a new Malachite blank without any problems. Will post pic on Monday. Thank you all for advice. Results were fantastic.