I have been sandblasting painted and rusted metals using sand with a compressor that is limited to about 7 cfm @ 80-90 psig. It works well on the engine tin pieces, but it is painfully slow going. I just switched over to 70 grit Aluminum Oxide media and it is marginally faster, but still too slow to get all the tin blasted in a reasonable amount of time. I know that I may be somewhat limited by my compressor and by the cheapo Harbor Freight gun that draws the media out of a 5-gallon bucket, but is there anything I can do to get this done any faster without buying a bigger compressor? Different media, pressurized media tank, better gun, etc. I'd like to be able to do this myself.

Short answer is no. I have a pressure pot, 3hp 135 psi compressor with 50 or 60 gallon tank and still hit flow limitations. Blasts great at 100 psi but once tank bleeds down to 80 psi and becomes air flow restricted, blasting efficiency drops.

I try to build in logical stop points to let the tank and efficiency recover before proceeding.

Pressure pot will improve your efficiency since it can accelerate media to about 90% Of air speed rather than relying on Venturi effect to suck up media with a slow media velocity.

I’m going to have a bunch of Tin to blast and powder coat. It will be outsourced due to my own equipment limitations and the time it will take.

I'm somewhat surprised you are able to make any headway blasting with such a small compressor.

A pressure pot will help, assuming you can keep it fed with air. A line air drier will help somewhat. But your compressor just does not have the balls to really go after blasting jobs.

Zach

Higher cfm will give you longer continuous work time.

with the above. My setup is similar to @Superhawk996 but have a 5 hp compressor and I still have to let it catch its breath frequently. The only thing I can see you might tweak is your pressure. Through experimenting, I found that I actually get more efficient blasting in the 40-60 psi range rather than cranked up high. When I hit some stubborn thick paint, coating, or corrosion, I kick the pressure up but for most stuff, a little lower pressure actually strips better and lets you blast longer between the compressor kicking in. Still, I think any gain will be marginal given your compressor limitations.

Sorry but you need a real compressor to be efficient with sandblasting.
I manged to find a guy out in the woods that had a dieselpowered compressor and a large blasting cabinet and his own powdercoating owen. Even with that big compressor it took 5-10 minutes to get the larger pieces spotless.

I learned the hard way. Pay the money and have it professionally done. Way too hard on home equipment. Most powder coaters will give a reduced price if they do the work.

I’m all about the DIY, but some things are just better left to the people equipped to do big stuff efficiently.

twin cylinder or a two stage also helps. ~$500 for a two stage 60 gal and $1K plus for a twin cyl.
Used of course....

Someday. . . That is dream garage gear!

Those numbers might be reversed. I have a twin cylinder but single stage. I think I paid $400 slightly used. Two-stage compressors I looked at were all much more expensive.

I did save about $600 blasting my car myself vs. paying the locals to do it, but boy do you pay for it in time and misery. Still, the savings more than offset what I spent on the compressor.

BTW, my compressor is oiless and I am NOT a fan. It builds pressure rapidly to about 105 psi but then struggles forever to climb to 120 where the cutoff is set. I'd gladly adjust the cutoff down but it is not adjustable. Not my best purchase but it gets the job done.

Continuous duty cycle use has little to do with the rated CFM. My fine for framing comp can't even keep up with an orbital sander. The comp motor gets real hot. The demand of a tool is key. Try a chem stripper. Less hassle to farm this task out. What's your time worth?

We have a rotary screw compressor and a blast cabinet with 150lbs of material at the shop and it still gets to be a drag when you have to do a lot of pieces.

I did get the guys to wear a respirator when they blast. The vacuum doesn't suck up all the dust.

First you need to know that a Harbor Freight compressor is not rated right. Or say true!

It does not matter what they tell you it does not put out the CFM they say. I run air sanders and my compressor works fine for all of my air tools but with a blaster you can always use more. I have a 30-year-old compressor cast iron not aluminum that was from a body shop and it never runs out or air but when I use it on my Bad Boy Blaster it still takes a long time.

The guys are right. Better to find a pro to do it as they can do it super fact.

If I have just a little bit to blast I use mine or it takes hours and it is really no fun. So, you are paying for it one way or another way.

Bob B


By the way: Mark has all the cool equipment

The last time I had to blast all the parts for a build I ended up just renting a gas powered compressor from a local place for $60/week. It worked really well. Just another option for you.

Most won't have a home workshop compressor that is truly big enough,I have a large twin cylinder unit which is the max I can run on single phase (ours is 220-240V),blasting requires #hitloads of air,gravity guns improve the situation but it's all about "air delivered".
Just done 80% of the tins on my current build ,I surface prepped with high speed wire brush and then sanded with emory tape ,a quick sweep blast with used slag grit (fine) and they came up nice after a coat of zinc rich primer.

Good luck.

I just take all my tin to the local powder coater, T4 all the tin blasted and powder coated costs me around $250, including the fan shroud painted silver/gray maybe $300 tops.

You do have to power wash heavy grease, do any repairs (welding etc) and straighten all the tin first but that's it, they do the rest.
Not worth my time even though I have the kit to DIY.

Taking a load of tin to my guy today.

Likewise,
When I did nime I took the tins, doghouse and all the brackets to a shop and had them blast and powder coat. Cost me a little time (I allowed them to wait until they had a bigger order to share some of the costs) but I had it all done for ~$150 and it looks better then I ever could have done it at home.

If you powdercoat the doghouse it WILL LOOK AMAZING. But you will need to run a grounding line from the body of the alternator to the chassis of the car, as the coating will block just enough of the ground path to be an issue (on my car it was resisting about 1.5 volts - and that's the difference between a strong running car and a dead battery at night as I learned the hard way).

Zach

What is the doghouse? , sorry hadn't heard that term in relation 914.



.

I think Zach is referring to the two piece fan enclosure (scroll casing) bolted to the front of the T4 case.

Yes, the big magnesium fan shroud is commonly called the dog house. Mine is PC grey and looks awesome. The metal was very tarnished after 40 years in an engine bay.

Zach

I just had to put this in:

Who Let the Dogs Out
Baha Men
Who let the dogs out
Woof, woof, woof, woof, woof
Who let the dogs out
Woof, woof, woof, woof, woof
Who let the dogs out
Woof, woof, woof, woof, woof
Who let the dogs out
The party was nice the party was pumping
Ah yepee ah yo
And everybody having a ball
Yepee ah yo
And tell the fellas stop the name callin'
Yepee ah yo
Then them girls respond to the call
I hear a woman shout outâ?¦
Who let the dogs out
Woof, woof, woof, woof, woof
Who let the dogs out
Woof, woof, woof, woof, woof
Who let the dogs out
Woof, woof, woof, woof, woof
Who let the dogs out
Last year in the dance you had a ball
You call me millibug and skettell
Get back gruffy, mash scruffy
Get back you flea infested mongrel
V3
Now I tell meh self dem man go get angry
Ah yepee ah yo
To hear…


Bob B

You can gang multiple compressors up to increase CFM's - they'll all start cutting out when they start coming up to pressures. just "T" them into a common manifold. I also used to use a big tank Air Compressor tank as a surge tank for extra volume.

Then I got a big compressor (used) as I'll use forever (as needed) of course.

That’s a job that’s best to be outsourced as sandblasting is disgusting. A cabinet helps, but proper equipment to do it efficiently is large and expensive for something that’s rarely used.

[quote name='GeorgeRud' date='Aug 29 2019, 12:53 PM' post='2742504']
. . . . sandblasting is disgusting.



You don't enjoy sand sticking to the back of your sweaty neck? I particularly love my eyeglasses getting fogged up in side the hood while wearing a respirator and/or having the sweat from my head drip on them.

Oh, forgot about the joy of getting sand out of my ears.

No idea what you're talking about.

If you do powder coat make sure the thread holes are protected and don’t get coated.

Home compressor is really setting yourself help for frustration.