Polishing internals data

Robotech · #71 (**permalink**) 12-03-2008, 12:22 PM

Quote:

Originally Posted by markerjunky

I polished mine the long way using each grit. Before the polish it was set at 285. After the polish it was measuring 365.

...and just how much would you charge to polish an A5? With my 3" barrel I get 210 out of it max. This kind of improvement would give me 285 easily without any other modifications. I'd even have some room for adjustability!

markerjunky · #72 (**permalink**) 12-03-2008, 01:40 PM

I was alarmed at the jump in FPS also. The field owner where I was at couldn't believe it and he's very experienced when it comes to the a5.

I'm a firm believer that the only way you'll learn is to do it yourself. It's very simple; just always err on the side of caution. Be conservative, gentle strokes, a soft back up, and proper grit sequences. Remember, we're dealing with very fine grits here. A 600 grit is only 16 microns in size. Part of that is imbedded in the resin and paper, so you won't even be penetrating the aluminum but maybe 10 microns. Use a soft backup and it'll be even less.

I've got zero experience with barrels as short as 3", but it seems to me like it would be something else causing your low velocity.

FurBall · #73 (**permalink**) 12-03-2008, 01:46 PM

my fps jumped quite a bit after I polished mine. in fact I could not get it to a safe level so I had to cut quite a bit off my drivespring. easily a 150 jump.

KRA SHARPSHOOTER · #74 (**permalink**) 12-03-2008, 03:01 PM

markerjunky, should I just press directly against the sandpaper onto the Receivers, or should I use the Rear Bolt to curve the paper evenly?

markerjunky · #75 (**permalink**) 12-03-2008, 04:05 PM

Whatever you use as a backup will definitely influence the way your sandpaper acts. If you use a hard backup like your powertube or rear bolt, the abrasive grain has no where to go but into the receiver half. It will be the most aggressive way of doing it. If you use a softer backup like a sponge or your finger, the abrasive grain can actually push back away from the aluminum receiver half. This will reduce the aggressiveness. The tradeoff is that you reduce consistency.

Since you are going about it in a proper grit sequence, and I think you know what you're doing, I would use the powertube and/or rear bolt to maintain or come close to the actual original a5 dimensions. But don't go at it for very long and remember to use light pressure. The paper is sharpest when it's new. My a5 had almost zero overspray, so I wasn't looking to remove any material. If you are removing overspray, I would remove that first and then go about the polishing process.

Good Luck and let me know how it comes out.

BTW, I mailed out the paper yesterday so you should see it soon.

KRA SHARPSHOOTER · #76 (**permalink**) 12-03-2008, 04:14 PM

OK, Thanks!

Guitarmech111 · #77 (**permalink**) 12-03-2008, 05:56 PM

What about using a polishing wad like NEVR-DULL?

It works great on my guitar frets. It leaves them like smooth glass. Aluminum rims shine like the sun. The chemicals and wad work great together. I haven't tried it yet, but may do so before this weekend.

MajorJohnson · #78 (**permalink**) 12-03-2008, 06:24 PM

Quote:

Originally Posted by markerjunky

If you know what Dykem Blue is you've got some experience in manufacturing or a machine shop. If anyone doesn't know, it's a metal dye that is applied to a part that is going to be machined or ground. It lets the operator know where the contact is on the workpiece because once it's touched by a grinding wheel or turning tool, you can visually see where the point of contact was.

It's a great idea!! If you have access to it, I think it would be a huge help because you'd actually be able to see what you've done. ..

Now it's been a long time since I used Dykem, so I'm not sure if you would want to reapply between each grit or not. I can't remember how easy it comes off. But I do know that on your first grit you'll probably start seeing lines of Dykem which lets you know that you're creating the valleys. I probably wouldn't reapply, but I'm not positive on that. The next grit sequence will make those lines even fainter and so on and so on. If you use Dykem, I'd be very interested to hear how it worked.

As for the different compounds, I'm not going to be any help to you on this. Sorry, but I just haven't been around it enough to know much. I've seen some posts on here about polishing different parts, but I can't remember who posted them. Maybe try a search and see what comes up.

For those who are interested, we are talking about the Dykem layout fluid that dries to a microscopic thin film and shows scratches, NOT the Dykem Hi-spot that never dries and is for transferring marks. It cleans up quite easily with regular rubbing alcohol.

I see your point about not sanding each grade until the blue is gone. I guess the ideal sequence would remove the last bit of blue with the highest grade paper, but I am still struggling with how to know just when I've done enough with one grade and move the the next. I have no "feel" for this.

I have done a bit of looking on the web for a chart that relates the grit rating of sandpaper to the particle size of other abrasives. What I have found is that the grit rating of the micro-mesh woodworking abrasive pads is not directly comparible to sandpaper grit ratings and that none of the charts that relate grit rating to particle size agree with each other worth beans.

Is there some source you can point us to for the definitive answer? In your experience, what is the particle size in microns for 2000 grit sandpaper?

markerjunky · #79 (**permalink**) 12-04-2008, 03:19 PM

Quote:

Originally Posted by MajorJohnson

For those who are interested, we are talking about the Dykem layout fluid that dries to a microscopic thin film and shows scratches, NOT the Dykem Hi-spot that never dries and is for transferring marks. It cleans up quite easily with regular rubbing alcohol.

I see your point about not sanding each grade until the blue is gone. I guess the ideal sequence would remove the last bit of blue with the highest grade paper, but I am still struggling with how to know just when I've done enough with one grade and move the the next. I have no "feel" for this.

I have done a bit of looking on the web for a chart that relates the grit rating of sandpaper to the particle size of other abrasives. What I have found is that the grit rating of the micro-mesh woodworking abrasive pads is not directly comparible to sandpaper grit ratings and that none of the charts that relate grit rating to particle size agree with each other worth beans.

Is there some source you can point us to for the definitive answer? In your experience, what is the particle size in microns for 2000 grit sandpaper?

Thanks for pointing out the differences in Dykem. I've seen it used several times but didn't know of the different types and their properties.

I found this resource for abrasive grit sizes while searching on Google. www.woodturners.org/tech_tips/misc-pages/abrasive_grading.pdf

I looked at it and the one I've got and there are some discrepancies, but no more than 1/8 of a micron, so close enough. It doesn't say what micron size 2000 is and neither does my chart. Mine does say 1200 is 6.5 microns and I think 2000 is 1.2 microns but I'm not sure.

The papers I'm referring to are the ones we manufacture and they are CAMI graded. Others might be Fepa graded and you will know because there is a "P" before the grit size, ie P600 grit, not just 600 grit.

Snipe07 · #80 (**permalink**) 12-12-2008, 12:22 AM

would using mothers polish and a powerball after polishing help any? or am i just nuts?

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