How do you enlarge tube hole?

[Timbo]

I seldom have problems with wood cracking when I press in the components, but some of the more brittle plastics can be an issue when the tolerance is too tight between the tube and the fitting. Also, I sometimes like to increase the inside diameter of the tube on really expensive blanks as a precaution. Currently I use a rat tail file to do this, but I'm thinking there must be a better/faster way. What do you use to accomplish this task? Thanks. (Note: the cracking is NOT due to glue being left on the inside of the tube)

 

[dansills]

I seldom have problems with wood cracking when I press in the components, but some of the more brittle plastics can be an issue when the tolerance is too tight between the tube and the fitting. Also, I sometimes like to increase the inside diameter of the tube on really expensive blanks as a precaution. Currently I use a rat tail file to do this, but I'm thinking there must be a better/faster way. What do you use to accomplish this task? Thanks. (Note: the cracking is NOT due to glue being left on the inside of the tube)

I do it on the lathe after drilling ... just some 220 wrapped around a smaller size punch and sand away. Also, lately I have found that on certain transparent acrylics the sanding really cleans up the inside of the blank too. (I learned this by searching the threads here on IAP)

 

[BRobbins629]

I use a split mandrel with some sandpaper or emory cloth in a Dremel tool. There's a few on the page of this site. Many others carry them. Search for split mandrel.

MonsterSlayer.com - Bits, Burrs & Mini Wheels

 

[KenV]

When a bit extra room is needed, I use a pin reamer. These come in stsndard sizes with a taper of 1/4 inch per foot. Hand used, they ease the entrance/start and slowly tighten. A sharpie mark on the inside of the tube will give you a visual guide if desired.

Loctite is your friend for securing the components.

 

[Buzzzz4]

I use a sanding attachment on my Dremel. Works like a charm! Also a great way to remove any glue inside the tube.

 

[plantman]

I also use a tapered reamer on my tubes. It takes off the small burr that is left on the inside of the tubes when you square the ends, and bevels the entrance for easier pressing on of the fittings. You could also buy an adjustable straight reamer that will enlarge the whole tube. These are a little costly, and you would need one for each size tube. A round or rat-tail file works on opening the blanks up. It gives you a little more controll of the amount you are removeing. I have also used a Dremmel with the small sanding drum bits if the shaft is long enough to reach 1/2 way into the blank. Sometimes I just hold the blank in my hand and run it up and down on the spinning drill bit in the drill press, using a little side pressure to increase the hole size. Don't tilt the blank side to side, you will only make the ends of your blank larger and the center will stay the same. Jim S

 

[skiprat]

I've had a certain kit that is often extremely tight to assemble so when I remember, I assemble the kit first, then knock it apart. This way the tubes get pre-stretched. :wink:

 

[nava1uni]

I use a chain saw file, because it is straight, unlike a rat tail file, there is no deformity of the tube. I slowly rotate the blank while I gently file. I also use a ream to remove any rough edge so there is no catch to cause any cracking. I have found that getting an acrylic too hot while polishing can cause tiny hairline cracks that don't become obvious, but can cause cracking during assembly. Also if your parts are not well aligned then cracking can occur very easily. Cracking is not always due to tightness or glue left in the tube.

 

[PenMan1]

I usually enlarge my tube hole with bacon, coffee and prune juice. When THAT doesn't work, I make an appointment for professional help. JUST saying..... YMMV

 

[thewishman]

I've tried almost all of those methods mentioned. After doing many tubes, one of the high-speed cutters on my rotary tool (HF version) does the most controllable job for me. I liked the little sanding drums, but they wore out very quickly.

 

[KBs Pensnmore]

I to have had this problem, due mainly to tubes being of different inside diameters. To get around this, I use a drill bit just a .0001 or 2 undersize of the component going into it. Make sure that plenty of lubricant (WD40) is used, as it also cleans out any residue glues.
Kryn

 

[rherrell]

I seldom have problems with wood cracking when I press in the components, but some of the more brittle plastics can be an issue when the tolerance is too tight between the tube and the fitting. Also, I sometimes like to increase the inside diameter of the tube on really expensive blanks as a precaution. Currently I use a rat tail file to do this, but I'm thinking there must be a better/faster way. What do you use to accomplish this task? Thanks. (Note: the cracking is NOT due to glue being left on the inside of the tube)

The correct drill bit. Get yourself a complete set of jobber length bits, fractional, letter and numbers, that way you'll always have the right drill.

This set is good enough for pen blanks.... Enco - Guaranteed Lowest Prices on Machinery, Tools and Shop Supplies

 

[soundman]

I'll second the chainsaw file I always take the bur of my tubes with a chainsaw file prior to mounting up.

Add a set of metric drills to your selection even the standard .5mm steps will give a couple of extra fractional fits between the factionals and the number letter drills.
If ya keen metric drills in .25mm steps can be had..take a bit of finding though.

cheers

 

[JD Combs Sr]

The correct drill bit. Get yourself a complete set of jobber length bits, fractional, letter and numbers, that way you'll always have the right drill.
This set is good enough for pen blanks.... Enco - Guaranteed Lowest Prices on Machinery, Tools and Shop Supplies

Ditto what Rick said. I also added a set of metric bits to make sure all sizes are covered. I will ream the inside of the tubes out with a bit that is the first size on a drill size chart that is smaller then the fitting being pressed into the tube. Never had any problems.

 

[BKelley]

If you want to enlarge the hole, use a reamer a coupla thousandths over normal hole size. Check your local machine shop supply house for availability.

Ben

 

[randyrls]

I take the bare brass tube and insert a transfer punch into the end about 1/4". With a gentle twisting motion enlarge the tube end until the fitting just slip into the tube. When assembling, Put a drop of thick CA on the inside of the brass tube and put the fitting on with a twisting motion to spread the CA. Don't put any CA on the fitting, you will get squeeze-out. DAMHIKT!