Help with drawing

[Tony Wells]

I have it drawn to scale, so if there are other dimensions you need, just let me know and I'll post a pic of it with those dimensions shown. I believe between the two drawings, you have enough information to machine the rail.

[Turbinedoctor]

Tony I really thank you and the others for your help but the numbers aren't adding up for me. Example: How far to cut the bevel in from the sides. Outer dim = .835 minus the smaller top diameter .6560 = .179 divide that by 2 = .0895. Your drawing is showing .0883 from top to bottom of that cut, which should be the same as the depth of cut from right to left. Am I looking at this correctly?

Next is the overall height from the bottom of the bottom cut to the top of the top cut. Drawing shows .2220. That minus the flat area of .0235 = .1985 divide that by 2 and I get .09925 where the drawing is calling for .0883.

Sorry to be such a bother but when I can't get the number to work out I get hung up and don't know which way to go. These are the diamentions that I am looking for, once I get the staright I feel I will be able to tackel this project.

Thanks again for all the input.

[claudef]

The most acurate way to measure these 45 deg. faces is over rollers.
You will still need to refer to the other sketch for demensions.
Attached is a sketch of picatinny rail I made last year but never posted.

[Tony Wells]

I drew that to, and my dimensions are from, the mid-tolerance sizes. That means for the 0.8350 +0/- 0.005 I drew to 0.8325. That should give you the correct calculations for what you seek. Same deal on the other dimension I bet. I didn't do the calculations, but if you are using the 0.164, you won't get the same thing I have using the mid-tolerance value of 0.1540.

I will grant you that engineering schools and standards teach that unilateral dimensions express the desired actual dimensions, then make allowance for manufacturing. In other words, the designers want the 0.835 dimension to be held at that rather than 0.8325, but allow it to be smaller.

[Highpower]

Just a couple of quick sloppy measurements for the halibut.

[stevec]

Huh?

[EdK]

(04-20-2012, 06:46 PM)stevec Wrote: Huh?

At first I thought this was about a model of some sort. Now I think it's about a gun part. Can someone in the know inform the rest of us what this part is that Turbo is asking about?

Ed

[Highpower]

Here you go......

Picatinny rail

[EdK]

That helps Willie.

Thanks,
Ed

[Turbinedoctor]

I for one think the drawings stink the way they show the diminions. I am finding that there seems to be a wide tolerance for these measurements. I just took my first attempt and slid an aimpoint sight on it and it fit just fine.

I still want to know what the actual numbers should be before tolerances.