machining the MiniBoy MarkI

A place for general potato gun questions and discussions.
User avatar
LeMaudit
Corporal 2
Corporal 2
Posts: 665
Joined: Thu Apr 16, 2009 2:48 pm

Donating Members

Sat Apr 09, 2011 4:50 pm

Here's a howto demonstrating the machining of the MiniBoy MarkI from this thread

My equipment are Sherline lathe (long bed) and mill. I'll be happy to try to answer any question about it, or the machining process demonstrated here. Note that I am in no way a machinist by trade, I learned by myself. So if some experienced machinist here want to share his knowledge and correct me, please do so ;-) I'm always happy to learn more.

If you have remarks about the missile itself, please share your thoughts in the original thread, not in this howto.

I will roughly follow this plan, scale = 1 pixel for 1/10mm.

Image
I often use this scale trick, So I can print what I want scale 10x, and just measure the sizes on paper with a simple ruler at a 10x enhanced precision (1cm=1mm)

Image
The nose is cut for a 3/4" brass bar. First, drill a hole (oops, forgot to put the macro mode on :roll:)


Image
Then, tap the hole. I do that by hand as I do not have power attachment for threading. I just turn the lathe chuck by hand, pushing the tailstock that hold the tap at the same time so it goes strait in the hole.


Image
While the brass rod is still perfectly centered, I remove the chuck and put it on the mill's rotary table. So I can remove some brass, to be able to fill it with heavier material later (lead or tungsten?)


Image
back to the lathe, I separate the proper length for the nose, using a cutting tool.


Image
Using a compound slide to cut at an angle, I approximate the cone. Simple trigonometry gave me 3 angles, from the original drawing. To hold the nose, I just used a screw and a nut to old it. This is why the drawing was designed like that, I already had in mind the way to hold and cut with minimal efforts :D


Image
A bit of sanding, and the nose is ready.


Image
For the fins, I will use the mill. Often when I cut on the mill, I machine behind a sheet of Lexan. In particular when I use saws. Better be safe...


Image
To make the fins, I use some brass flat stock. First sliced on the mill.


Image
I mill it strait on all sides, both pieces at the same time.


Image
Then I slice the interlocking groove.


Image
A bit of sanding to make then look pretty while they are easy to handle separately.


Image
I assemble them, gently taping with a plastic hammer.


Image
Then I cut the same angle on all sides to mimic the original drawing.


Image
A bit more sanding, and the fins are ready. I may make then a bit more aerodynamic by removing this square edge later.


Image
The fins tip (is there a proper name for that?). A rod if first drilled and taped on the lathe (same process as for the nose). Then a cross slice is cut on the mill.


Image
I decided I needed a reduced diameter, to increase rigidity. It would have been better planning to cut it before I made the slicing. Oh well...


Image
The cone is cut, this time by rotating the headstock.


Image
A bit of polishing, and it's ready for assembly 8)


Image
While the lathe headstock is at the same angle, I cut a rod of aluminum.


Image
Then drill it to the proper diameter, so the recess plug from the fins tip can fit in.


Image
I then go to the mill, and drill some exhaust holes. Just in case they'll be needed later.


Image
back to the lathe, the piece is cut to the proper length so the diameter at the cut match the fins tip.


Image
Final piece.


Image
It match the fins tip quite nicely.


Image
I machine the body part from a 1" aluminum rod, drill it with a 1/2" drill bit (starting from a much smaller diameter and increasing step by step)


Image
then I make a little recess to install the nose, fixed in place with a long threaded rod that goes through the chuck, and turn to the exact same diameter both parts.


Image
same operation for the tail, after turning the body 180°, I machine a cone at the same angle...


Image
... and repeat the cut and different angles to approximate a rounded surface.


Image
After a bit of sanding, the body is completed.


Image
I need a couple of nuts to make an internal separation for the weight. Sure a couple of standard 10-24 nuts and a washer could do... but why not go fancy and make my owns? The brass rod is drilled, then threaded.


Image
And turned to exact diameter.


Image
On the mill, I cut some flats.


Image
Then separate the nuts on the lathe using a cutting tool.


Image
Done.


Image
Here's the final result


Image
For scale :)

Image
And the various parts
Last edited by LeMaudit on Tue Apr 12, 2011 5:37 pm, edited 4 times in total.
warhead052
Staff Sergeant 3
Staff Sergeant 3
Posts: 1769
Joined: Mon Mar 21, 2011 5:41 pm

Sat Apr 09, 2011 5:33 pm

Nice, and these are used for?
User avatar
LeMaudit
Corporal 2
Corporal 2
Posts: 665
Joined: Thu Apr 16, 2009 2:48 pm

Donating Members

Sat Apr 09, 2011 5:53 pm

Christmas decorations :D
warhead052
Staff Sergeant 3
Staff Sergeant 3
Posts: 1769
Joined: Mon Mar 21, 2011 5:41 pm

Sat Apr 09, 2011 11:31 pm

Haha, nice. They look extremely well made.. If I had money I would possibly buy a couple off you...
User avatar
Crna Legija
First Sergeant 2
First Sergeant 2
Posts: 2333
Joined: Sun Jul 20, 2008 5:14 am
Location: australia

Sun Apr 10, 2011 12:26 am

wow how much did that lathe/mill set you back?

looks good, shame the nice shiny brass will probably not be found
'' To alcohol... The cause of, and solution to, all of life's problems.”
--Homer Simpson

Add me on ps3: wannafuk, 8/11/11 cant wait
turner
Specialist
Specialist
Posts: 113
Joined: Fri Aug 07, 2009 11:48 pm

Sun Apr 10, 2011 2:16 am

Wow that's more machining then almost every cannon on here
User avatar
jakethebeast
Corporal 5
Corporal 5
Finland
Posts: 945
Joined: Sat Jul 03, 2010 4:20 pm
Location: Jakes cave

Sun Apr 10, 2011 4:45 am

That is awesome! i hope you still can find it after those long range shots :D
User avatar
LeMaudit
Corporal 2
Corporal 2
Posts: 665
Joined: Thu Apr 16, 2009 2:48 pm

Donating Members

Sun Apr 10, 2011 8:03 am

Crna Legija wrote:how much did that lathe/mill set you back?
I have this package deal:
Image

Current price (US) is $2400. Note that I have no relationship whatsoever with Sherline. I just love their tools and their range of accessories.

I bought it long ago when the $CAN was not that good compared to $US so I feel cheated looking at the prices again :lol:

If you feel a bit entrepreneurship like I am, know that I refunded the package + a workshop full of tools (drill press, band saw, grinder, you name it...) after 2 years selling items I machined with it.
Wow that's more machining then almost every cannon on here
Machining is an hobby in itself. I am lucky to have a very broad range of interest, guns included :D But making metal chips is fun by itself.
User avatar
ilovefire
Corporal
Corporal
Posts: 511
Joined: Sat May 22, 2010 6:48 am

Sun Apr 10, 2011 8:32 am

i can not possibly tell you how much i want that package, i would have a lot better and more formidable air guns if i were to have those it would also make it easier for me to make this PCP stile gun i have started, lets just hope i dont get bored of it before i finish
why make it if it dosent shoot?
User avatar
LeMaudit
Corporal 2
Corporal 2
Posts: 665
Joined: Thu Apr 16, 2009 2:48 pm

Donating Members

Sun Apr 10, 2011 9:05 am

Dear Santa... :D

One very nice features for those machines is that they can be bought bits by bits... you start with a lathe, add a milling column, later a bed mill while sharing the motor, then some accessories, then a second motor, etc...
User avatar
ramses
Staff Sergeant 2
Staff Sergeant 2
United States of America
Posts: 1679
Joined: Thu May 29, 2008 6:50 pm

Sun Apr 10, 2011 10:44 am

Dear Grizzly: please get your 0704 mill back in stock before that 10% coupon expires. Or I could buy the "mini mill"...

Nice work! I see that the nose is an ogive. I'd hang it on my Christmas tree.
POLAND_SPUD wrote:even if there was no link I'd know it's a bot because of female name :D
User avatar
LeMaudit
Corporal 2
Corporal 2
Posts: 665
Joined: Thu Apr 16, 2009 2:48 pm

Donating Members

Sun Apr 10, 2011 7:59 pm

More photographs for your entertainment :D
User avatar
kjjohn
Specialist 2
Specialist 2
Posts: 270
Joined: Sat Jul 11, 2009 3:54 pm
Contact:

Mon Apr 11, 2011 9:11 am


If you feel a bit entrepreneurship like I am, know that I refunded the package + a workshop full of tools (drill press, band saw, grinder, you name it...) after 2 years selling items I machined with it.
What kind of things have you sold? I am thinking of buying a mini milling machine and doing sort of the same thing.
User avatar
LeMaudit
Corporal 2
Corporal 2
Posts: 665
Joined: Thu Apr 16, 2009 2:48 pm

Donating Members

Mon Apr 11, 2011 11:03 am

I have sold 3 kind of things:

- Miniature objects at 1/12 scale for doll collectors. Typically replica of household items, one of a kind, and on the expensive side :) Note that I'm not a collector myself... of any kind... so I don't care selling of giving away things I do ;-)

- 1/35 cast items in resin for military modelers. After a few hundred casts, I was bored to death...

- which lead to selling mold masters in metal for company that produce resin items at a larger scale than me.
User avatar
LeMaudit
Corporal 2
Corporal 2
Posts: 665
Joined: Thu Apr 16, 2009 2:48 pm

Donating Members

Tue Apr 12, 2011 5:38 pm

The machining is completed. I hope you enjoyed the photographs :)
Post Reply