erikgreen
Captain
- Joined
- Jan 8, 2007
- Messages
- 3,105
I sorta felt like I needed to type this, it's probably boring to read, but typing it felt good, so it was worth posting 
So last night I was trying to get some things done on my newly acquired used lower half of my pre-alpha sterndrive. I decided to do more than just bolt it on and go... the old drive was looking a bit worn anyway, and the new half had been painted, but it was basically a rattle can job over the original paint.
So I decided the "right" thing to do is to blast the paint off with walnut shells, which are supposed to be great for aluminum blasting, nice and gentle. I bought a can of self etching primer (no one seems to have zinc chromate) and a can of midnight black quicksilver paint.
I picked up a $25 box of walnut shell blast media, 12 grit, at harbor freight, and got it home. I took my pressure tank blaster out, which I hadn't used in a couple months, and filled it up, then ran up the air compressor to a full tank.
The compressor is a frankenstein... I have an old portable Quincy compressor running on a half horse giant motor that I got with my house, and it feeds a tank from my old Sanborn compressor, which got a crack in its pump two winters ago. They're all hosed together with a regulator on the sanborn and a pressure cutoff on the quincy. I probably get about 4 CFM from this setup, more while the tank lasts. Not enough for continuous blasting, but enough to do maybe a minute's worth followed by ten minutes of doing something else.
But after getting ready and putting the half drive in my blast cabinet, I only got a few tiny spurts of media... I figured it was a clog, and tried to clear it, no luck. I then figured out the walnut shell media was much too large a grit for the cheap blaster. Grr. Two grains of the stuff side by side was enough to clog it.
Then I figured that I'd have to use some of the coal slag I had for rust removal. It's a little hard on aluminum, but if I was careful I could get the drive clean and then sand a bit later to give it a better surface.
Over the next hour and a half I tried to get the blaster unclogged... I switched media, switched it again, used a welding rod to clean the nozzle, on and on and on... I got maybe one side of the drive done in little bits of clean blasting. I finally decided to give up on that clogged blaster and just run and get one of the cheap "spot blaster" guns HF sells.... they only hold enough for 30 sec of blasting, but that was better than fighting with my pressure tank. I really only wanted to get the drive clean anyway, not blast a trailer.
So I went and spend $19.95 on one... cute little thing, not much to it. I hooked it up, put some slag in it.... nothing. Tried changing settings, nothing. I couldn't even get slag to drop out if I tilted the gun down.
I figured out that the gun must have a screen on the media hopper that keeps out larger chunks of media... which includes all the slag grit in the size I had. Probably I could blast soda out of it. I looked at the "manual" that came with it, and it says plastic or glass bead media. Sigh.
So after all that I gave up on blasting... tonight I'll go buy a jug of citrus stripper and clean the paint that way, then do some wet sanding. That's less cleaning of grit afterward anyway.
It hurts that I'm not flush with cash at the moment and I spent $50 on stuff that didn't help me, but more annoying on top of that is not getting anything done to show for it.
I just hate evenings when I can't go in the house and have a sense of satisfaction from getting something done. Sometimes nothing works right, and I have to admit defeat.
But I don't have to like it.
Erik
So last night I was trying to get some things done on my newly acquired used lower half of my pre-alpha sterndrive. I decided to do more than just bolt it on and go... the old drive was looking a bit worn anyway, and the new half had been painted, but it was basically a rattle can job over the original paint.
So I decided the "right" thing to do is to blast the paint off with walnut shells, which are supposed to be great for aluminum blasting, nice and gentle. I bought a can of self etching primer (no one seems to have zinc chromate) and a can of midnight black quicksilver paint.
I picked up a $25 box of walnut shell blast media, 12 grit, at harbor freight, and got it home. I took my pressure tank blaster out, which I hadn't used in a couple months, and filled it up, then ran up the air compressor to a full tank.
The compressor is a frankenstein... I have an old portable Quincy compressor running on a half horse giant motor that I got with my house, and it feeds a tank from my old Sanborn compressor, which got a crack in its pump two winters ago. They're all hosed together with a regulator on the sanborn and a pressure cutoff on the quincy. I probably get about 4 CFM from this setup, more while the tank lasts. Not enough for continuous blasting, but enough to do maybe a minute's worth followed by ten minutes of doing something else.
But after getting ready and putting the half drive in my blast cabinet, I only got a few tiny spurts of media... I figured it was a clog, and tried to clear it, no luck. I then figured out the walnut shell media was much too large a grit for the cheap blaster. Grr. Two grains of the stuff side by side was enough to clog it.
Then I figured that I'd have to use some of the coal slag I had for rust removal. It's a little hard on aluminum, but if I was careful I could get the drive clean and then sand a bit later to give it a better surface.
Over the next hour and a half I tried to get the blaster unclogged... I switched media, switched it again, used a welding rod to clean the nozzle, on and on and on... I got maybe one side of the drive done in little bits of clean blasting. I finally decided to give up on that clogged blaster and just run and get one of the cheap "spot blaster" guns HF sells.... they only hold enough for 30 sec of blasting, but that was better than fighting with my pressure tank. I really only wanted to get the drive clean anyway, not blast a trailer.
So I went and spend $19.95 on one... cute little thing, not much to it. I hooked it up, put some slag in it.... nothing. Tried changing settings, nothing. I couldn't even get slag to drop out if I tilted the gun down.
I figured out that the gun must have a screen on the media hopper that keeps out larger chunks of media... which includes all the slag grit in the size I had. Probably I could blast soda out of it. I looked at the "manual" that came with it, and it says plastic or glass bead media. Sigh.
So after all that I gave up on blasting... tonight I'll go buy a jug of citrus stripper and clean the paint that way, then do some wet sanding. That's less cleaning of grit afterward anyway.
It hurts that I'm not flush with cash at the moment and I spent $50 on stuff that didn't help me, but more annoying on top of that is not getting anything done to show for it.
I just hate evenings when I can't go in the house and have a sense of satisfaction from getting something done. Sometimes nothing works right, and I have to admit defeat.
But I don't have to like it.
Erik
