Drilling thin wall tubing - any hints and tips?

alan2525 · 20-08-2008

For a 16mm Loco I need to drill some holes for the various boiler fittings in the boiler barrel.

Boiler barrel is 35mm diameter copper tube and holes need to be 9mm diameter, wall thickness is just over 1mm.

How would you do it? I just centre drilled on a pillar drill and opened up with a cone drill and then enlarged the hole with a round file to fit the threaded bushes. Probably not the best way but it worked...

**GEEDUBBYA** · 21-08-2008

Howdy Alan,

Ok, here while back someone asked about bending tubing and how to keep it from collapsing as they bent it. I suggested filling the tubing with sand and taping shut both open ends. This might be a solution for you if you are afraid the copper tubing might collapse when drilled. However, sand might not be real good for your drill bit.
Plain dirt may work better, or even stuffing a potato into the tube (allowing the edge of the tubing to cut off all unwanted parts of the potato as you shove the "spud" down the tube. We load our "tater-cannons" in this manner and the potato forms to the cannon barrel and would do the same in the tubing).
The potato would provide a strong internal re-inforcemnt for the tubing while drilling.

These are just a few thought, maybe others will have better ideas.

Have a good day,

Greg aka GEEDUBBYA

alan2525 · 21-08-2008

I was thinking of maybe turning a piece of wood to fit inside the tube to allow it to be held in a drill vice to stop it from deforming. The main issue is that copper tends to snatch on a drill bit so I was using a cone drill but they dont drill very precisely, seem to wander a bit. As I have a few holes that need to be in a line along the tube I'm a bit concerened that one of these may wander off, leaving me with a funnel and a safetly valve at different angles...

...by the way how many 'tater cannon do you have?

Quote:

Originally Posted by GEEDUBBYA

Howdy Alan,

Ok, here while back someone asked about bending tubing and how to keep it from collapsing as they bent it. I suggested filling the tubing with sand and taping shut both open ends. This might be a solution for you if you are afraid the copper tubing might collapse when drilled. However, sand might not be real good for your drill bit.
Plain dirt may work better, or even stuffing a potato into the tube (allowing the edge of the tubing to cut off all unwanted parts of the potato as you shove the "spud" down the tube. We load our "tater-cannons" in this manner and the potato forms to the cannon barrel and would do the same in the tubing).
The potato would provide a strong internal re-inforcemnt for the tubing while drilling.

These are just a few thought, maybe others will have better ideas.

Have a good day,

Greg aka GEEDUBBYA

**GEEDUBBYA** · 21-08-2008

Howdy Alan,

Ok, When i worked as a machinist in the transformer industry, we used alot of copper and there is a way to sharpen a drill bit in such a manner that it is for the most part flat with only a small tip in the center. A good example of what i am talking about would be for you to draw a "stick seagull" like you did when you was a kid...(a stretched out letter M) then flip it over and thats what the tip of the drill bit should look like for copper. except you dont want the edges of the bit to be as long as the tip in the center. (see picture below)
As for tater cannons, i only have one and i havent shot it in several yrs. however back at the transformer factory (the power supply type, not the robots), i made hundreds of them for other ppl out of PVC pipe. The attached drawing shows how they are constructed. Once it is dry, you force a potato into the barrel up to the reducer, then unscrew the sewer access cap on the other end and spray in most any aerosol spray that will burn and reseal the cap. then just twist the striker. Its a "controlled explosion" if you can call it that, a potato fired by one of these will probably break bones. they also may be illegal in some areas so check before you build and fire one.

Have a good day and you can probably see one being fired on youtube.

Greg

tag · 21-08-2008

Looks like a wood drill bit would maybe one of those might work could be worth a try

jspitza · 21-08-2008

Hi Greg and hope you had a nice summer!
I lived with a bunch of crazy guys when I was in my early 20's. We made the potato gun on our property. We lived on a apple orchard and also fired the big juicy ones! And it was one of the most amazingly powerful things I ever saw and dam funny at the time!. I'm not going to go into the details of how we powered it-suffice it to say we were both lucky and stupid........
Oh why did you have to post this plan! Now, I have to make one!!!!!!!!!

alan2525 · 21-08-2008

Quote:

Originally Posted by GEEDUBBYA

Howdy Alan,

Ok, When i worked as a machinist in the transformer industry, we used alot of copper and there is a way to sharpen a drill bit in such a manner that it is for the most part flat with only a small tip in the center. A good example of what i am talking about would be for you to draw a "stick seagull" like you did when you was a kid...(a stretched out letter M) then flip it over and thats what the tip of the drill bit should look like for copper. except you dont want the edges of the bit to be as long as the tip in the center. (see picture below)
As for tater cannons, i only have one and i havent shot it in several yrs. however back at the transformer factory (the power supply type, not the robots), i made hundreds of them for other ppl out of PVC pipe. The attached drawing shows how they are constructed. Once it is dry, you force a potato into the barrel up to the reducer, then unscrew the sewer access cap on the other end and spray in most any aerosol spray that will burn and reseal the cap. then just twist the striker. Its a "controlled explosion" if you can call it that, a potato fired by one of these will probably break bones. they also may be illegal in some areas so check before you build and fire one.

Have a good day and you can probably see one being fired on youtube.

Greg

I've got a couple of drill bits like this?

Supposed to be self centering, I got them from screwfix in the uk, looks very similar to the pattern you showed above.

peter22 · 21-08-2008

Hi Alan
You could try lathe center bits - I tried on 15mm drilled ok no snatching, only other advice masking tape down center of tube draw C/L for alignment, when cutting copper tube reverse hacksaw blade - cut on the backstroke
peter

**GEEDUBBYA** · 24-08-2008

Howdy Alan,

Sorry for the late reply. That looks like the tip I was describing. Of course we ground our own tips on our drill bits ( I was kinda "ticky" about how I wanted the bit i was using to be sharpened).
The beauty of this type tip is that, being "flat", it doesnt take as much material as it turns, therefore you are almost shaving the copper. This style tip can also be dulled ever so lightly to drill brass (which "grabs" even more than copper). By dulling the tip, it allows the bit to remove even less material preventing the bit from unching through like a sharp bit would do. You are practially "milling" the material off with this flat type bit.
One word of advice if you try to sharpen them, it may take you several attempts to get the center of the bit just right if you have never sharpened a bit in this manner. Another tip would be to be sure and remove metal from the backside of the edge of the bit when sharpening to allow the shavings to exit the work area freely.

I hope i have made some sense to you and hope it helps.

Have a good day,

Greg

To Jspitza: have fun and be careful lol ( Although this is my drawing for the cannon, I originally found a drawing on the web years ago for them and after building so many of them, I started getting requests for plans for them).

and to every one else, please remember that these cannons may not be legal in all areas, check the laws in your area before you build one, I wouldnt want anyone to get arrested for a terrorist weapon (they make a very loud BOOM and will sling a potato 100 yards easy and will like I said above, break bones. Oh, and there is always the risk of a material failure which would be the biggest explosion you have ever been one foot from lol. So Please becareful.