TheSamba.com :: View topic - Sandblasting

Tue Jun 06, 2017 10:03 pm

Will this sandblaster allow me to do the entire body inside and out along with the pan?

https://www.harborfreight.com/air-tools/air-compre...67847.html

Is it recommended to purchase the warranty they offer when purchasing it?

Tue Jun 06, 2017 10:50 pm

In the big scheme of things I know very little about air compressors but enough to know that compressor won't supply near enough air to do squat for sandblasting.
I have a 25 gallon compressor and it can barely keep up with soda blasting small parts.

My understanding is you need a 60 gallon tank minimum.

Search on sand in the compressor thread, I believe some information comes up.
Direct sand search link there

Tue Jun 06, 2017 11:09 pm

EverettB wrote: In the big scheme of things I know very little about air compressors but enough to know that compressor won't supply near enough air to do squat for sandblasting.
I have a 25 gallon compressor and it can barely keep up with soda blasting small parts.

My understanding is you need a 60 gallon tank minimum.

Search on sand in the compressor thread, I believe some information comes up.
Direct sand search link there
Thanks. I was afraid of that. It seems in order to get to that mark costs quite a bit of money.

Thanks for the thread. I was searching for "harbor freight" and "sand" and came up with different results. I'll read the thread to see what I can come up with.

Wed Jun 07, 2017 7:21 am

Although it is technically possible to blast the entire car with that compressor, you will find the time involved is not worth the effort. The low air volume delivery of that compressor would increase the amount of time needed to deliver a given amount of media. That would in turn make the compressor run non-stop after the first minute of blasting which will lead to an overabundance of water in the lines. You would need an aftercooler between the pump and the tank followed by a water separator/trap or about 50' of metal pipe with a water trap at the end after the tank to help reduce the condensed water in the lines. Both of thees options are a good idea no matter what compressor you choose. Research them both to help you decide which is best for you. A desiccant air dryer would help remove any moisture remaining in the air stream.

My old compressor had the following specs:
PSI: Max 125
Tank: 20 Gal.
Displacement: 14 CFM
Air Delivery: 10.3 SCFM@40PSI / 8.5 SCFM@90 PSI
I used this compressor to blast my pan but it was a slow and frustrating effort. I was using a 50# siphon feed media balster with crushed glass. I could get through 1 50# load of media then the amount of water in the line would begin to clog the blaster.

The conventional wisdom is to get the biggest compressor you can afford and/or fit in you work space. Although true it is not always necessary. large capacity will reduce the amount of time the pump runs but what you are really interested in is air volume and duty cicle. I got away with 8 CFM @ 90 PSI. If I had installed an aftercooler or a condensation loop, I believe I could have successfully done more work with less frustration.

One way to achieve high CFM with low cost equipment is to chain several small compressors together.
here is one example: https://www.youtube.com/watch?v=YGYgQO5TFto

Here are some examples of an aftercoolers:
http://blog.cnccookbook.com/2011/09/06/aftercooling-a-compressor-to-cut-down-on-moisture/
https://www.youtube.com/results?search_query=compressor+aftercooler

Here is an examples of a water separator/condensation loop:
https://www.youtube.com/watch?v=VFFPIRLx_ro

...and desiccant dryers:
DIY using Galvanized pipe: http://www.garagejournal.com/forum/showthread.php?p=4128720#post4128720
DIY using a Whole House water Filter (Silica gel is a better desiccant choice): http://www.cnczone.com/forums/articles/212488-cnc.html
Retail (DeVilbiss QC3 Air Filter and Dryer): https://www.amazon.com/DeVilbiss-130525-QC3-Filter-Dryer/dp/B002PR8ZXK

Your choice of media blaster will also influence how smoothly the process will go. A siphon feed unit is small and portable but will use more air/pound of media than a pressurized media blaster. The pressurized units can be had at Harbor Freight for around $100 US or on Craig's List for a bit less. If you build a blasting booth out of PVC and plastic sheeting you can cut down on the amount of media needed to blast the entire car because you can reclaim and reuse the media several times before it becomes too fine to be be effective. I found that the Glass media sold at Norther Tool ( Clean Bite Crushed Glass Blast Media — 50 Lbs., Medium Grade
Item# 49360) will last about ten uses before it is too fine to use. This media is also safe as it contains non-crystalline silica and will not lead to silicosis, but a respirator is HIGHLY RECOMMENDED.
Here is an example of a blasting/painting booth: https://formufit.com/pages/pvc-spray-paint-booth

...we're all in this together.
Emil

Wed Jun 07, 2017 7:30 am

nope... compressor would run the whole time and last about 4 hours before burning down.

Wed Jun 07, 2017 10:38 am

The price of the compressor is what is getting me. It seems I will need to spent over $800 in order to be able to do this. If I do that, I may as well try painting the vehicle too.

Thanks for the input.

Wed Jun 07, 2017 10:40 am

kawfee wrote: The price of the compressor is what is getting me. It seems I will need to spent over $800 in order to be able to do this. If I do that, I may as well try painting the vehicle too.

Thanks for the input. I would use paint stripper for the majority and then.. use that tinny compressor that is a good deal for the money to do places you cant get with stripper.. or places you do not want to use stripper.. it will work.. but only for a few minutes maybe 5 before you need to give compressor time to fill tank again and start over.. you can not run that compressor none stop.. it will burn up..

Wed Jun 07, 2017 10:45 am

I've got two cars to do. Each one is about $1000 to paint at the shop I take it to. I'm assuming the paint cost to be around $500 of that but I am guessing.

If I took the 2k I was going to use to paint and bought the tools for myself I could warrant the cost of the large compressor.

Wed Jun 07, 2017 10:55 am

kawfee wrote: I've got two cars to do. Each one is about $1000 to paint at the shop I take it to. I'm assuming the paint cost to be around $500 of that but I am guessing.

If I took the 2k I was going to use to paint and bought the tools for myself I could warrant the cost of the large compressor. as long as you know what you are doing.. you can warp stuff real easy ..

Wed Jun 07, 2017 12:00 pm

Here is the compressor I purchased to replace the aging "Tank of death" 20 gal. compressor I was using.
NorthStar Belt-Drive Stationary Air Compressor — 3 HP, 60-Gallon Vertical Tank - $569. It is the Northern Tool house brand but appears to be made by PUMA: (Puma 3-HP 60-Gallon (Belt Drive) Single-Stage Air Compressor. It is $130 cheaper than the PUMA and carries a 4 Yr. warranty if used in a noncommercial setting; both units have overwhelmingly positive reviews. It will deliver 11.3 CFM at 90 PSI and 12.5 CFM at 40 PSI, more than enough to media blast and paint with an HVLP gun. They also offer free delivery if you don't need lift gate service or free delivery to your local Northern Tool store. You may also find an on-line coupon code for $50 off a purchase over $250 (google "Norther Tool coupon code.")

I hope the info is helpful
Emil

Wed Jun 07, 2017 12:47 pm

That's a lot better than the $800 I thought I would need to spend. Thanks.

Evil_Fiz wrote: Here is the compressor I purchased to replace the aging "Tank of death" 20 gal. compressor I was using.
NorthStar Belt-Drive Stationary Air Compressor — 3 HP, 60-Gallon Vertical Tank - $569. It is the Northern Tool house brand but appears to be made by PUMA: (Puma 3-HP 60-Gallon (Belt Drive) Single-Stage Air Compressor. It is $130 cheaper than the PUMA and carries a 4 Yr. warranty if used in a noncommercial setting; both units have overwhelmingly positive reviews. It will deliver 11.3 CFM at 90 PSI and 12.5 CFM at 40 PSI, more than enough to media blast and paint with an HVLP gun. They also offer free delivery if you don't need lift gate service or free delivery to your local Northern Tool store. You may also find an on-line coupon code for $50 off a purchase over $250 (google "Norther Tool coupon code.")

I hope the info is helpful
Emil

Sat Jun 10, 2017 7:33 pm

I purchased the Northern Tool One.

In order to get started I see I will need at least the following:

Regulator
Sand Blaster Tank
Air Hose
Respirator

Is there anything else I might need and is Harbor Freight a good place to get everything else?

Evil_Fiz wrote: Here is the compressor I purchased to replace the aging "Tank of death" 20 gal. compressor I was using.
NorthStar Belt-Drive Stationary Air Compressor — 3 HP, 60-Gallon Vertical Tank - $569. It is the Northern Tool house brand but appears to be made by PUMA: (Puma 3-HP 60-Gallon (Belt Drive) Single-Stage Air Compressor. It is $130 cheaper than the PUMA and carries a 4 Yr. warranty if used in a noncommercial setting; both units have overwhelmingly positive reviews. It will deliver 11.3 CFM at 90 PSI and 12.5 CFM at 40 PSI, more than enough to media blast and paint with an HVLP gun. They also offer free delivery if you don't need lift gate service or free delivery to your local Northern Tool store. You may also find an on-line coupon code for $50 off a purchase over $250 (google "Norther Tool coupon code.")

I hope the info is helpful
Emil

Sun Jun 11, 2017 6:29 am

to sand blast a body inside and out will kill any home type compressor , save your headache and just have it blasted.
fabricator john
you should be able to have it done in the 3-500 dollar range

Sun Jun 11, 2017 7:57 am

When I have to replace my 5hp 20gallon compressor it's going to be with this if I can't find a 6-6.5 single phase.
http://www.homedepot.com/p/Puma-40-Gal-5-HP-Electr...lsrc=aw.ds

-A bigger tank only stores engergy.
-Blasting at high pressure warps sheetmetal

Sun Jun 11, 2017 8:45 am

fabricator john wrote: to sand blast a body inside and out will kill any home type compressor , save your headache and just have it blasted.
fabricator john
you should be able to have it done in the 3-500 dollar range

I can buy the compressor with 4 year warranty for that price.

When I spoke with northern tool they told me the compressor would work just find sandblasting.

Sun Jun 11, 2017 2:27 pm

kawfee wrote: I purchased the Northern Tool One.

In order to get started I see I will need at least the following:

Regulator
Sand Blaster Tank
Air Hose
Respirator

Is there anything else I might need and is Harbor Freight a good place to get everything else?

I was as clueless about compressed air as anyone who may find this post informational so I am sharing what my research has yielded in the hope of saving others time and effort looking for this information. I encourage anyone considering this information to find corroborating data.
I am still in the process of building out my air delivery system. Garagejournal.com and Practicalmachinist.com have been great sources of compressor and air delivery information. I have spent the last few months researching air delivery systems and have come up with the following:

1) Regulator - Get a 1/2 in.regulator with good flow characteristics. (See above websites for info on this subject)

2) Sand Blaster Tank - The general consensus is that a pressure blaster will be better and more efficient than a siphon style blaster. The Harbor Freight pressure blasters can be made to work well. Search YouTube for mods and details.

3) Air Hose - At a minimum, use a 3/8 hose of the shortest length needed to do the job. A 1/2 In. hose will deliver the lowest air flow restriction and is good for 100 Ft. Please note that the 100' number applies to total lengh of plumbing thus you must include any metal tubing used for distribution and cooling (See item 5 below). Use 3/8-high flow fittings if possible. e.g. Milton S-766 3/8" V Style High Flow Coupler

4) Respirator - I have found the 3M 62023HA1-C Professional Multi-Purpose Respirator, Medium to serve as a great dust mask for blasting. When the time comes I will buy new vapor cartridges and it should serve well as a painting mask. See the Full face or half face respirator thread for a discussion face masks. NOTE: If using solvent based paint containing isocyanates, only a fresh air system and adequate ventilation will provide a SAFER environment.

5) Moisture/Water in the lines - You will need to remove as much water from the air as possible by lowering the dew point of the COMPRESSED air. See this article for valuable information. LINK
There are two ways to accomplish this. The first is to use an aftercooler between the air pump and the receiver tank ( I mentioned this earlier in the thread,) the second is to Cool the air with at least 50 Ft. of metal pipe after it leaves the receiver tank. I have chosen to go with the aftercoolre approach for two reasons, it takes up less space and will boost the amount of compressed air in the tank because cooler air will have a higher compression rate.
EDIT: Formula to substantiate above statement found HERE and an explanation HERE
"Using Charles' law (V2/V1 = T2/T1), the increased volume based on my temperature measurements will be:
427.59°K / 308.70°K = 1.38.
Meaning there's a 38% increase in air molecules stored in the tank under best case/worst case scenarios. Of course, it's a 60 gallon tank and it's going to contain 60 gallons of air no matter what. The "increased" storage capacity will be realized by the pressure in the tank not dropping considerably once the air cools down."
There is also anecdotal evidence that suggests the compressor will run cooler with an aftercooler (see above post for examples of air cooling methods.) I have chosen to go with the B&M trans cooler for its compact size and efficiency and am in the process of purchasing same. I will update this thread when I have usage data.

6) Desiccant dryer - This will be your last step in the moisture elimination process but will only be needed for painting, CNC work, or a plasma cutter. There are many DIY versions available as well as commercial ones. (See above post for details and examples)

7) Air filtration - the best approach is a multi-tierd one. Place a 40 Micron filter/water separator after the regulator (and cooling/water separation loop if used) followed by 5 micron filter, and finally a 1 Micron or lower oil coalescing filter. See the websites listed above for options.

8 ) Blasting media - I used Clean Bite Crushed Glass Blast Media — 50 Lbs., Medium Grade sold at Northern Tool @ $9.99 (6-11-2017) for a 50 Lbs. bag. This is the best price I have found on effective and safe blasting media. See my previus post for details. I reused a 50 Lbs. bag about 10 times before the media became too fine and lost effectiveness as a rust remover. The fine media was still able to cut paint easily.

There are many opinions on this subject, fortunately, and unfortunately, they are all mostly or entirely correct. When taken out of context, the biggest, baddest 2 stage 80 Gal. compressor is the ideal way to go, however, when viewed within the context of the home DIYer with limited space and budget, the tool needed only has to serve the needs of the tasks that it will be charged with. I can confidently state the a 20 gal, 8 CFM @ 90 PSI compressor coupled with a 50 Lbs, siphon feed media blaster CAN and WILL work to media blast an entire Karmann Ghia chassis. It was not done in a day, but the task was completed.

The point made above about warping metal with a media blaster can be true under a certain circumstances. If SAND is used with a HIGH VOLUME, HIGH POWER, COMMERCIAL blaster, warping can very easily occur. On the other hand a 100# pressure blaster running at 90 PSI with a small nozzle is highly unlikely to get any sheet metal hot enough to warp; it is mostly incapable of covering a big enough area in a short enough amount of time to allow for heat buildup. As always, keep the nozzle moving and don't blast one are for too long.

This information is provided in the spirit of helping a fellow DIYer finish his/her project. Please verify all claims before acting.

...we're all in this together.
Emil

Sun Jun 11, 2017 5:32 pm

Quote: it is mostly incapable of covering a big enough area in a short enough amount of time to allow for heat buildup.

It's not the heat it's the collision of the sand against the metal similar to a miniature hammer hitting the metal a countless amount of times. The metal is stretched out.

Sun Jun 11, 2017 5:54 pm

You should just have it done. It takes a ton of volume to blast a car. Then you have to get something on the metal immediately or it will start to rust.

Sun Jun 11, 2017 7:18 pm

I'm sand blasting it then spraying it with primer. Then I will take it to the autobody shop and let them deal with it. I've got at least two cars to do like this. If I paid someone to do it I would pay more than the tools I bought. Now I get to keep the tools at the end for other things. Maybe I will even try spraying it myself.

Thank you for all the points. It's interesting to see everyone's view points.

Sun Jun 11, 2017 7:37 pm

You should try spraying it for sure.
Do you know what your going to spray it with? A direct to metal material I hope!