Hexagonal Alu Bar for MonoCores

[PaulNoiseLess]

Hi,

Any experiences out there with hexagonal Alu bars ?

I have to take a decision on my new .3xx MonoCore and looks to me easier to drill than circular bars. I have a 3 jaws chuck for building the prototype.

Also, any tip on turning in the lathe ?.

Best,

Paul

[pneumagger]

Why would it be any easier to drill on a lathe than a round bar?
With a 3 jaw chuck, I don't think it would matter.

In the end though, you still have to round out the bar.
Also no t difficult, but still takes more time.

[PaulNoiseLess]

Hi,

What I’m planning with the Hexagonal Bar:
1) Bullet hole with the Lathe.
2) Barrel hole with the Lathe.
3) Round up the ends (with the bench grinder) to form a cylinder with the Lathe (slowly till I get a perfect circle). Thread with taps & dies holding the tools with the tail stock.
4) Drill Chambers and Baffles with the drill press.
5) Thread caps.

(What I want is a thread less tube)

Step 4 is easier with the Hexagon. Right ?. I drill in the flat faces.

Best,

Paul

[ghostdog662]

Why would you use a bench grinder ? Just put a facing tool in your tool holder and run it across until you achieve the diameter you need.

I still don't understand why you would consider a hexagon when your tube round. You have a round tube, stick a round bar in there.

You should be drilling with a center drill first through all of your holes so that flat surface of the hexagon isn't necessarily help.

[PaulNoiseLess]

Hi,

Thanks for the advice !

All my bench tools, except Lathe, are not made for precision works: Stock holder for my Drill Press is flat and I usually have a nightmare finding centers. Flat surfaces are easier to work with. I can also use my Sand Disk to flatten the vortexes a little bit for better tool penetration.

I’ll drill center the side holes with the drill press so I do not have to care about alignments in the Lathe.

I’m about to have a very good deal for Hexagonal Alu due to last minute order cancellation (50% off) and due to the lack of tools and materials around here I think it’s a good choice.

Using the grinder is just to give some “help” to my tool once on the tool post and turning.

Best,

Paul

[Historian]

Hi,

What I’m planning with the Hexagonal Bar:
1) Bullet hole with the Lathe.
2) Barrel hole with the Lathe.
3) Round up the ends (with the bench grinder) to form a cylinder with the Lathe (slowly till I get a perfect circle). Thread with taps & dies holding the tools with the tail stock.
4) Drill Chambers and Baffles with the drill press.
5) Thread caps.

(What I want is a thread less tube)

Step 4 is easier with the Hexagon. Right ?. I drill in the flat faces.

Best,

Paul

Paul, round stock is easily held on drill press with, say, L.S. Starrett 51293 - 271A V Blocks 1-1/4" Cap and
clamps. I have used said Vees against a 90 degree, cheap, blocks.

Hope you find this useful.

[PaulNoiseLess]

Hi,

Here is what i’m thinking about:

The design is based on one I found in this Forum but Hexagonal Bar
It’s 9 inches long x 1.5 inches (ID Tube) x 400 grams. The Core is 1 inch flat-to-flat faces.
All Alu 6061 for subsonic ammo (.3xx)
Floating core and thread less tube
The Core threads to the Barrel so I can work on very low tolerance bullet hole (for .3xx I’m going to do 8.25 mm)

I’m also thinking on more axial holes but due to the fact it’s a floating core (plenty of room) I don’t think I need them. Right ?

I can make it only with the small Lathe I have and the Drill Press.

What do you guys thin ?

Best,

Paul

[mx201er]

I believe he is saying it is harder to drill cross holes in a round bar, because the bit tends to wander and it is harder to measure hole placement since there is no straight edge to measure from.. It tried my first monocore with square aluminum bar stock for that reason the first time, but the interrupted cutting of that magnitude beats up the lathe quite a bit.. It seems like a hexagonal bar would work pretty good, eliminate the drill bit from wondering, and make it easier to measure layout. Then just face half of it on the lathe and turn it around to do the other half; no bench grinder, that would just make things asymmetrical.
If you have a mill handy you don't have to worry about the bit wandering, as mill bits do not flex, and it is easier to just start with a round bar.

But if you wanted to do it the way you have planned, it will work just fine! I would just leave out the bench grinder part