Gunsmithing Finished my scope base...

B

Blackout

Private
Minuteman
Jun 14, 2008
73
0
43
Poinsett Co, AR
www.astraybullet.com
#1
I finally got my 1-piece base machined. I wouldn't actually say it was finished since I still need to put a finish on it. It took me 2 tries on making it. The the double angle tool I ground was oversized and forgot to compensate for it. So the first one's rails were not to spec.

r7mnt_1.jpg

r7mnt_2.jpg

r7mnt_3.jpg


I didn't do any cant on it. I wanted to test it out and see how well my contour fit the receiver. Everything worked great and I will make another with a 20moa cant to it. I 3d machined the bottom side of it so I wouldn't have to make any special work holding to get the right angle.

I was thinking of making a batch of these after I put a hundred rounds down range with it. If anyone is interested, I'll post more information.
 
#4
Re: Finished my scope base...

I used 7075. I don't mind sharing, but I can't remember the exact diameter that ended up with. It was trial an error on that part. I machined 4 small blocks testing the radius until I got one that fit good. When I get to the shop in the morning, I'll post it.

Off the top of my head, I know there was a 0.12 (+/- .005) difference in height between the front and the rear. The front was a 1.352 diameter.
 
#9
Re: Finished my scope base...

@ TCA4570
I had 3 processes in machining it. First was cutting the bottom of the block. 2nd was doing the top contour, drilling, slots, and angles. 3rd was 3d'ing the bottom.

3d'ing the bottom took right around 14 minutes, running 50 IPM. That method seemed to be the best route on testing. I didn't want to make an angled fixture or anything that I might have to remake several times until it was right. If the base was held vertically and secured, you could do the same cut in a minute or two. Speed vs. flexibility.

@ JPOutfitters
Well it was the best location for lighting. She is ok with it ever since I added a room on to the house. She was out shopping and I had the table saw in the kitchen. She came home to a room with 5 gallons worth of saw dust on the floor. ;-)
 
#12
Re: Finished my scope base...

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: USMC7980</div><div class="ubbcode-body">I would be interested in getting one, let me know what happens when you decide. </div></div>

me too.
 
#13
Re: Finished my scope base...

@ keydiverfla
PM me if you have any questions for your project.

@ crumpmd
I use a Haas VF1.

@ 1sikpupi...
I talked to a few people and have some idea of what I will end up doing. I was thinking for the price to be $50.

That will include:

- Any choice of cant 0/10/20/30.
- Snail mail shipping.
- Re tempered after machining.
- Blasted and duracoated.

Depending on the interest, I'll op to get them type 3 anodized instead of duracoat.

I will be altering the design to be a bit taller (0.125" more) and adding a spirit level to the rear. It will be pocketed for the level and the level will be glued in. I am open to any other suggestions or features to add/change.

I'm not positive on the rules for this stuff, but it seems I will do it in the group buy section or whatever. That will be after more testing.
 
#14
Re: Finished my scope base...

What temper 7075 are you starting out with??.. Are you treating the Alum before machining to prevent warpage then re-aging?. What temper are you offering to take them to above>

50 IPM is too slow for 3D machining..you can cut ur time by 70% if you do it right.

How straight are they?? any straightening ops?
 
#15
Re: Finished my scope base...

I prefer to start slow and improve upon the process rather than to start hard only to repeat after mistakes. Not to mention I needed to make it for my rifle build. The more times I have to machine something, the longer it takes me to have a good day at the range.

As for the temper, it is certified as T6 when I get it. I re temper at 340 degrees for about 8 hours. Which T6 is similarly performed at that. I am only aging the surface again so that a spray on finish will hold up better when rings are clamped on. I'll skip the process if I am anodizing. I can't say that it returns to a true T6 temper, but it does seem to help in the long run.

They are straight as the holes on the receiver. The holes on the base are machined in the same process as the rails so everything is parallel. They are center drilled, drilled, and then angled with a 1 flute 60 degree router bit. The screws are also turned in a lathe to true up the chamfer.
 
#16
Re: Finished my scope base...

sorry black out but machining aluminum is way easier then you think. I dont like the large cut out in the base. There is no need for it if the round does not hit it upon ejecting. You will learn how fast you can do it and it will make th finish even nicer when you do. Anodizing is the way to go with aluminum but you must allow for tolerences.
 
#17
Re: Finished my scope base...

To me machining is like shooting. Until you have your variables figured out, you take it slow and think it through. When I get a new gun I don't just jump into a competition with it. When I design a part, I don't know how strong the end result will be or how rigid the setup is until I try it.

I'd rather run something at half the speed and not make mistakes since the sole purpose to create myself a base to save me from having to drop $100 for one. If I break a tool or mess up a couple of blocks trying to make it, I have defeated the purpose of saving money.
 
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