Machining radius slot

This topic has 8 replies, 4 voices, and was last updated 12 May 2012 at 10:57 by alan knight.

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11 May 2012 at 18:20 #6138
alan knight
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@alanknight67321
Machining radius slot
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11 May 2012 at 18:20 #90618
alan knight
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@alanknight67321
Hi have a job to inlet a cyliner into a gunstock, I need to produce a slot of aproximately 30mm dia 25mm deep. I have a milling machine but am struggeling to find what would be the appropriate cutter, buying a 30mm ball nose cutter is out of the question as the cost would be extorsionate. i was wondering if a form of flycutter could be ground to do the bussiness?
11 May 2012 at 18:32 #90621
JasonB
Moderator
@jasonb
If the gun stock is wood then can you use a router bit? Though finding a metric one may be a problem. You could grind up a bit of gauge plate and mount that in a holder which would suffice

Do you have a proper DRO if so the arc function can be used to creater the "U" shape with a series of cuts from a smaller ball mose mill.

Or mount the gunstock on the lathe and cut with a boring head

J
11 May 2012 at 18:42 #90623
alan knight
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@alanknight67321
No dro as yet spent an arm and a leg on the workshop this year so cant see one any time soon. I could rough the lions share out with an endmill then make a guage plate cutter to finish the job
11 May 2012 at 22:20 #90643
I.M. OUTAHERE
Participant
@i-m-outahere
Hi Alan .

I would do a search on the internet to see if there are any gunsmithing sites or any footage of inletting a stock on youtube .

I take it that you are inletting the Barrel slot ?

Is the Receiver /Action inletted yet ?

What is the stock made of ?

Is this rifle a modern sporter or is it an older military rifle .303 or a Mauser etc ( the barrels were mostly encased in timber )

You will find there is a good chance that the Barrel is tapered so using a 30 mm cutter will leave a parrallel slot and this means the gap at the sides will either get bigger (if the cutter is the same dia as the thickend of the barrel) or get smaller because the cutter is the same dia as the thinner end of the barrel .

Is the barrel to be full floated ? ( not touching the stock anywhere except directly in front of the receiver /action) so the slot needs to be half a millimeter or more wider and deeper than the barrel

Are you going to Glass bed the action or barrel ( an epoxy used to fill gaps around the receiver and can be used to supprot the barrel but it is usually only the receiver that gets done .)

I used a home made rasp to get it close then fettled it with sandpaper wrapped around different sized mandrels , it took some time and patience but worked well .

For the rasp i used the blade for one of those cheese grater type wood rasps , the type that has a removable /replacable blade .then i cut out a piece and rolled it around a mandrel that was made to allow for the thickness of the blade and depth of its cutting teeth .

I then tack welded it arond the mandrel an welded on a handle .

It didnt take long to get the groove roughed out .

When ever you do anything to a firearm it will affect the accuracy of it so be carefull .

Ian

Edited By IAN B on 11/05/2012 22:21:42
12 May 2012 at 09:11 #90654
M0BND
Participant
@m0bnd
Try tilting the head of your milling machine over at an angle. There is a formula to work out the angle and diameter of cutter required, I cannot find it at the minute but I have done this as an apprentice about 22 years ago This was when we made scribing blocks with rads down the sides. If I find it then I will let you know.

Until then, try this at about 45 degrees and use a small fly cutter at 30mm diameter.

Andy.
12 May 2012 at 09:40 #90656
M0BND
Participant
@m0bnd
On a side question, what is the gun? I have a few myself and enjoy .22 match rifle and clay shooting.
12 May 2012 at 10:12 #90661
JasonB
Moderator
@jasonb
I don't think the tilting head method will work as the slot is U shaped. The tool needs to swing a larger radius than that required so would end up cutting the two sides of the U. I think it probably only works where the depth is less than half the diameter, I've only ever used it for shallow dishing so have not tried it to the limit of whats possible.

Unless the head could be tilted to 90degrees then a boring head would do the job. This is really the same as setting the work in the lathe as I said above

J

Edited By JasonB on 12/05/2012 10:13:29
12 May 2012 at 10:57 #90663
alan knight
Participant
@alanknight67321
Bleeding hell lads I leave the forum for one night and it all go's potty lol.

Right the stock in question is a airarms s10 the action is a s10 with a bsa ultra pressure cylinder that been regged by John bowket, so the cylinder itself is a constant diameter. Im having to cut the end off the stock and then I will be laminating on an african blackwood snable end thus why I need to look into inletting the fore end to accept the cylinder. As it would just be the pressure cylinder touching the stock and not the barrel as that is free floated off the action I dont need to have a clearance fit to stop harmonic resonance affecting accuracy I just need it to fit with a fine degree of clearance to allow the action to be removed if nessessary but to be snug when the stock bolts are tightened to stop any slop in the rifle.

I have checked youtube but there are mostly videos of cnc maching on the action inletting or people doing it all by hand neither of which has been much of a help. Iv been a joiner for 15years so im well aware how to inlett the action by hand but I have a perfectly good milling machine sat there and want to get my moneys worth out of it.

May have a horizontal mill coming in a couple of days so that opens up a few possabilities.
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