Advertise on Bikeforums.net



User Tag List

Results 1 to 21 of 21
  1. #1
    Senior Member
    Join Date
    Dec 2007
    Location
    NYC
    Posts
    93
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    Sandblasting Question

    I need to sandblast some frames, not many, and I won't be doing this often.

    I'm currently trying to do a local barter for an air compressor (which will come in handy outside of the sandblasting). I've got some offers, but for some pretty low tier compressors. What is the bare minimum of a compressor I can get away with and still be able to use a hand sandblasting *** with its own reservoir? Will I be able to blast at all with, say, 4 CFM at 100psi? If not, what is the lowest I can go before I'm just giving the frames a sand massage.......

    I don't mind if it takes awhile, and I realize a smaller compressor will cut in and out on me fairly often.....but anything is better then the tedium of stripping by hand

    Thanks for the help!

  2. #2
    Senior Member
    Join Date
    Apr 2009
    Location
    New Rochelle, NY
    My Bikes
    too many bikes from 1967 10s (5x2)Frejus to a Sumitomo Ti/Chorus aluminum 10s (10x2), plus one non-susp mtn bike I use as my commuter
    Posts
    20,737
    Mentioned
    46 Post(s)
    Tagged
    1 Thread(s)
    The sandblasting *** will have specs listing the needed air volume/pressure capacity. You need a compressor with bigger capacity.

    Without know what the *** needs, it's impossible to say how much air is enough.
    FB
    Chain-L site

    An ounce of diagnosis is worth a pound of cure.

    “Never argue with an idiot. He will only bring you down to his level and beat you with experience.”, George Carlin

    “One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN

    WARNING, I'm from New York. Thin skinned people should maintain safe distance.

  3. #3
    Senior Member
    Join Date
    Dec 2007
    Location
    NYC
    Posts
    93
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Good point. I don't actually have a *** yet, and I was looking at some of the relatively cheap ones ($40 or less), but could certainly tailor the *** purchase to the abilities of my compressor. So, a better question might be, what's the lowest volume/pressure capacity that a sandblasting *** can use and still be effective?

  4. #4
    Senior Member
    Join Date
    Apr 2009
    Location
    New Rochelle, NY
    My Bikes
    too many bikes from 1967 10s (5x2)Frejus to a Sumitomo Ti/Chorus aluminum 10s (10x2), plus one non-susp mtn bike I use as my commuter
    Posts
    20,737
    Mentioned
    46 Post(s)
    Tagged
    1 Thread(s)
    Quote Originally Posted by Smithie View Post
    Good point. I don't actually have a *** yet, and I was looking at some of the relatively cheap ones ($40 or less), but could certainly tailor the *** purchase to the abilities of my compressor. So, a better question might be, what's the lowest volume/pressure capacity that a sandblasting *** can use and still be effective?

    You're still doing it backward. Don't buy a *** based on capacity, buy capacity to match a ***.

    Since you don't yet have a compressor, shop the guns first. That'll give you a clear idea of how much compressor you'll need.

    One thing I can tell you is that most small compressors, fall into either of two categories. Nail *** and similar low volume tools and spray painting, which usually need less than 4cfm at 90psi.

    Larger power tools tend to need more volume, and I suspect anything bigger than a small hobbyist sandblaster will too.
    FB
    Chain-L site

    An ounce of diagnosis is worth a pound of cure.

    “Never argue with an idiot. He will only bring you down to his level and beat you with experience.”, George Carlin

    “One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN

    WARNING, I'm from New York. Thin skinned people should maintain safe distance.

  5. #5
    Senior Member mrrabbit's Avatar
    Join Date
    Dec 2007
    Location
    San Jose, California
    My Bikes
    2001 Tommasini Sintesi w/ Campagnolo Daytona 10 Speed
    Posts
    3,180
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    Bottom line as FBinNY is trying to tell you is that if you do not provide a big enough compressor capacity and psi wise for the *** - you'll spend WAY more time waiting for the compressor getting recharged than getting more actual work done.

    Even with a huge 40 gallon compressor powering the one I used two weeks ago - it came out to about 2 minutes recharge per 1 minute of work. It was a patience test already...took me fifteen minutes for the fork and an hour for the frame.

    Imagine what it'd be like if your compressor was so small that its 2 minutes recharge and 15 seconds of work.

    Research...research...match and then buy. Don't cut corners on *** vs. compressor cap.

    =8-)
    4000+ wheels built since 1984...

    Disclaimer:

    1. I do not claim to be an expert in bicycle mechanics despite my experience.
    2. I like anyone will comment in other areas.
    3. I do not own the preexisting concepts of DISH and ERD.
    4. I will provide information as I always have to others that I believe will help them protect themselves from unscrupulous mechanics.
    5. My all time favorite book is:

    Kahane, Howard. Logic and Contemporary Rhetoric: The Use of Reason in Everyday Life

  6. #6
    Senior Member Iowegian's Avatar
    Join Date
    Dec 2005
    Location
    Boulder, Colo
    Posts
    1,733
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Don't forget to check into the cost of the media you will be using, it can add up. I'm in about the same position and already have a decent compressor but I decided I'd just pay for the service on the few occasions I need it. I've heard that the siphon style guns are nearly worthless for anything but very small jobs so you'll probably want to get a pressurized tank type of blaster. You will also need some protective gear and a place to do the work.

    I just had a frame stripped and powder coated. The total cost was about what just the blaster tank would cost. The outfit that did it has industrial equipment and buys their materials in bulk. They also do this everyday and do high quality work. As much as I'd like to do the stripping myself to save $30+ per frame on the re-finish, the numbers just don't add up. YMMV

  7. #7
    Senior Member catonec's Avatar
    Join Date
    Apr 2009
    Location
    burlington VT.
    Posts
    2,224
    Mentioned
    3 Post(s)
    Tagged
    0 Thread(s)
    Is stripping the paint w/chemicals an option for you? it might save all this confussion, and equipment purchases.
    2010 Kestrel RT900SL, 800k carbon, chorus/record, speedplay, zonda
    1997 Trek ZX6000, 6061w/manitou spyder, xt/xtr, time atac

  8. #8
    Senior Member
    Join Date
    Aug 2005
    Location
    Pittsburgh, PA
    My Bikes
    '''96 Litespeed Catalyst, '05 Litespeed Firenze, '06 Litespeed Tuscany, '12 Surly Pacer, All are 3x8,9 or 10. It is hilly around here!
    Posts
    25,493
    Mentioned
    6 Post(s)
    Tagged
    0 Thread(s)
    Also, be sure your electrical service is capable of handling the compressor you buy. Most compressors over 1.5 HP require a 220 V circuit.

  9. #9
    Senior Member
    Join Date
    Dec 2007
    Location
    NYC
    Posts
    93
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    So, I definitely agree that buying a nice, big compressor would make this a non-issue. But.....the only reason I even have the option of doing this is through trade (for an old welder I no longer need). I can scratch together enough for a ***, but buying a large compressor, even a well used one, is out of budget by quite a ways. So, if I need to do this shoestring, and knowing that I am in for some frustration for doing so, can I still put together a package that will work albeit slowly and annoyingly?

    This is currently the compressor that someone is offering up: http://www.sears.com/craftsman-4-gal...p-00916638000P

    It's 4 gallon, 1hp, and very, very small. It maxes out at 125psi, but the cfm are quite low at such a high pressure. But, he would include cash with the trade which gives me some extra play room for my ***, medium, and safety gear purchase.

    I did some looking, and *** options at such a pitiful volume/pressure are either this: http://www.amazon.com/Gilmour-70HDG-.../dp/B0006U66CA

    Or this: http://www.amazon.com/Paasche-AECR-R...4371565&sr=1-2

    The Gilmour is a least a real ***....but even its low requirements of 4cfm at 70psi are barely in range of this compressor, so I imagine there will be long recharge periods. I am nowhere near versed enough to do the maths on exactly how long though.

    The other option is that Paashe etching brush. I don't really know much about it except that this compressor would certainly be well within its volume/pressure needs, which means it might be slow going, but there would not be much waiting involved in the process.

    So, outside of the fact that this is an extremely slap-dash set-up I'm trying to build......can I get it to work?

  10. #10
    Senior Member
    Join Date
    May 2008
    Location
    Houston, TX
    My Bikes
    Giant FCR3, Cannondale Synapse Carbon
    Posts
    191
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    It would take a very long time to strip a frame using one horsepower; the spray pattern would be about the area of a dime. I would bet the finish could be sandpapered off faster. My mid-size blast cabinet used a compressor rated at 18 CFM @ 90 PSI and it ran continuously when I blasted. You might do better to farm out the blasting. I would suggest using glass bead blasting; it is far less erosive to the base metal than sand.

  11. #11
    Senior Member Ira B's Avatar
    Join Date
    Aug 2010
    Location
    Coupeville, WA
    My Bikes
    84 Raleigh Technium- 89 Shogun Mt. Bike-96 Miyata 914
    Posts
    880
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    I used to restore old VW bugs and have done a lot of sandblasting of parts ect...

    My advice. Calculate how many cubic feet per min. of air and at what pressure you will need for the *** you are using.....then set up for 5 times as much.
    If you have not done any sand blasting before you will be surprised at how much air it takes, the time involved and how much work it is.
    WEAR A RESPIRATOR!!!
    Yep, THAT Ira

  12. #12
    Senior Member BCRider's Avatar
    Join Date
    Mar 2008
    Location
    The 'Wack, BC, Canada
    My Bikes
    Norco (2), Miyata, Canondale, Soma, Redline
    Posts
    5,430
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    First of forget the Paasche etcher. That size of "toy" is intended for jewelry or other very small jobs requireing intracate control. I'd go so far as to say that the area of coverage will be more about the size of a felt pen dab than a dime. It's intended for very small size and intracate jobs. Doing a bicycle is just not in the cards for such a unit. Neither is the normal sands or other media. In short that unit for a bicycle frame would be like trying to paint a battleship with a 1/2 inch artists brush.

    The Gilmore *** at least looks more like what you need. But without knowing the actual consumption in volume at what PSI you're in the dark. In googling for "low volume media blasting" I turned up this interesting link;

    http://www.harborfreight.com/gravity...***-93221.html

    Note the low volume of only 1.7 cfm. The compressor you listed shows a rating of 4 cfm so it should be able to keep up fairly well. This particular *** would appear to be fairly well suited to doing a small job such as a bicycle frame. And if you watch the video they do mention that this particular *** is only used with glass bead media. But from the looks of it doing a number on the painted metal it seems like about the right size and type of media.

    You're going to need to learn a lot about media blasting. On any sort of good frame "sand" is the last thing you want to use. Most of the media grits which cut fast will also cut at the metal below the paint. The less abrasive media that will cut the paint away but leave the metal below intact are going to be a bit more specialized and likely not that cheap. Or if you insist on doing the job with the cheaper but more abrasive sand then you'll need to vary the operating pressure to set up a spray that minimizes any cutting of the metal. And when you do that it's not all that fast a job. Or as noted to use the glass bead media mentioned already.
    Model airplanes are cool too!.....

  13. #13
    Senior Member
    Join Date
    Sep 2007
    Location
    Gaseous Cloud around Uranus
    Posts
    3,358
    Mentioned
    2 Post(s)
    Tagged
    0 Thread(s)
    The little bucket type *** you showed will work with that compressor.It will be a slow process but it will do the job and will make a HUGE mess.Some of the better ones,you will be able to change the tip size,depending on your compressor output.Even with a say 3/32 or 1/8 inch tip,real small in sandblasting terms,it will put out a pattern about the size of a pencil eraser or so.

    The little etching *** is for delicate work,modeling,glass,it will only take real fine media.You won't live long enough to complete a frame and fork.It would be like painting a car with an airbrush.

    One of the advantages of using a cabinet style,syphon or pressure,is that the media has many feet of hose in which to build up speed before impacting the part.Something you don't get with a *** style.So with low pressures,not much reserve air,and limited impact power,what does this all mean.

    You should use maybe 30-40 lbs of air pressure,low by blasting standards,use an aggresive media(silica sand,coal slag or a man made media,say Starblast),and be prepared to use up some time.Go slow,the aggresive media with etch the crap out of the metal if your not careful,you'll have to sand it when your done.

    Silica sand(sandbox sand) and coal slag(glass like remnants of coal production) is cheap,aggressive and DEADLY!!! If you use this,stand downwind,use a respirator not a mask and goggles.The fine dust,stuff you don't see,gets in your lungs and shreads them.If you inhale enough you will cough up blood.This is no joke,that's why there is a skull and crossbones on the bag!

    For your purposes,sand or slag will work,an engineered media,while much less deadly,will cost too much to just blow around the yard.
    Last edited by Booger1; 08-26-11 at 11:44 AM.
    Everything should be as simple as possible...But not more so.---Albert Einstein

  14. #14
    slow as I ever was Ex Pres's Avatar
    Join Date
    Dec 2007
    Location
    an imposter living in the 35223
    Posts
    5,653
    Mentioned
    5 Post(s)
    Tagged
    0 Thread(s)
    72 special CNC ___________ 72 Frejus (ala Legnano) __73 Holdsworth Record
    78 Raleigh Professional_____ 80 Ranson_____________ 80 unknown French (SS)
    82 Peugeot PXN10_________83 Trek 620 (nee 600)____ 85 Gianni Motta
    85 Trek 560______________88 Guerciotti GLX
    90 Miele Gara_____________02 Casati Dardo (g/blue)__02 Casati Dardo (y/blk)
    03 Casati Dardo___________08 BF IRO (fixed)________10 Vassago Fisticuff (IGH)

  15. #15
    Member brokencase's Avatar
    Join Date
    Feb 2011
    Location
    Pennsylvannia
    My Bikes
    Scott CR1, Dawes SST-AL
    Posts
    44
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    I did some DIY sandblasting about two years ago using this.
    http://www.harborfreight.com/portabl...kit-37025.html

    I was cleaning up some old wire wheels for a british sports car. I used play sand and laid out a large tarp in the back yard. You must use a respirator and other protection.
    It's a big mess.

    My advise is that you skip the sand blasting and use paint stripper instead.

    It's not worth the investment and you are better off taking it to someone to sandblast it for you.

    Sand blasting is best for smaller items that you can fit into a sandblasting cabinet.

  16. #16
    SE Wis dedhed's Avatar
    Join Date
    Apr 2005
    Location
    Milwaukee, WI
    My Bikes
    '68 Raleigh Sprite, '02 Raleigh C500, '84 Raleigh Gran Prix, '91 Trek 400
    Posts
    2,199
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    I've done some old farm tractors with my Craftsman 4HP, 25 gal, rated at 7.0SCFM. Using a siphon hopper unit and sometimes had to wait for it to catch up or cool down as it isn't rated for 100% duty cycle.

    I used black beauty media. Of course this wasn't thin wall bike frames
    http://www.reade.com/eastern-region-(usa)/56

    I made a booth out of some old plywood and tarps so I could reuse the media and not make a big mess out in my driveway. Fortunately we have a cabinet at work that fits a bike frame.
    '68 Raleigh Sprite, '02 Raleigh C500, '84 Raleigh Gran Prix, '91 Trek 400

  17. #17
    Lover of Old Chrome Moly Myosmith's Avatar
    Join Date
    May 2011
    Location
    NW Minnesota
    Posts
    2,544
    Mentioned
    3 Post(s)
    Tagged
    0 Thread(s)
    I've done a lot of sandblasting up to the size of truck boxes and frames and you will be very disappointed by the results of using a small "spot" blaster with an undersized compressor. I still have a spot blaster that I use with a 3/4 hp, 11 gal portable compressor and would never use it to strip an entire frame. It would be painfully slow and make more mess than it is worth. I use it mainly for giving aluminum parts a satin finish or removing rust. Unless you are going to do a lot of frames, you might be better off making a deal with a local shop that does sandblasting. My local guy said he'd do a frame and fork for $35. If you are going to have the frame professionally painted or powdercoated, many shops either have, or have contacts for sandblasting and will do it as a package deal for a decent price.

  18. #18
    Senior Member
    Join Date
    Dec 2007
    Location
    NYC
    Posts
    93
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    First, thanks for all the input. I really appreciate it. And yes, I know that if this was just one frame, out-sourcing would be far, far cheaper and easier than what I'm trying to do. But, I have at least three frames I want to strip right now, one just for painting, and two which need tube replacements. If I can get this sandblasting system to work, I figure I will be stripping at least one or two frames a year.

    So, I got lucky, and somebody actually paid me cash for the welder I was trying to barter. That, and I noticed through BCRider's recommendation of the smaller *** at Harbor Freight that they were having a huge sale at the local store. All told, using the money from the welder sale and about 20 bucks out of pocket I was able to get an 2HP 8 gal compressor (4.5CFM @90PSI, 5.5CFM @40PSI), the 1.7 CFM spot blasting ***, hose, couplers, oil, all the safety equipment mother hen could desire, and a lvlp touch-up paint sprayer which this compressor can handle.

    So now, my next question. I am planning on making a poor man's blast cabinet out of heavy cardboard. I bought 5lbs of 40-70 grit glass media, and I was considering lining the make-shift cabinet with a heavy duty plastic (at least 3mm) to make the media recovery easier. But, will this glass media just eat right through the plastic (the *** will be on 90psi shooting out the 40-70 grit glass)? Am I better off just trying to seal up the cardboard as well as possible and creating a small reservoir that way?

    Thanks again for all the help!

  19. #19
    Senior Member
    Join Date
    May 2008
    Location
    Houston, TX
    My Bikes
    Giant FCR3, Cannondale Synapse Carbon
    Posts
    191
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Good choice, the glass beads, but they will eat through cardboard, or plastic, and then pieces of your cabinet will fall into the media and clog-up the *** when you recycle the beads. Consider building a wooden cabinet lined with sheet metal. A portion of your glass beads will turn to dust from impact so you'll probably need more than the 5 pounds. You'll need a window in your cabinet to see what you are doing and evening length rubber gloves to protect your hands and arms. Through your window, you won't see much, other than flying dust, unless you hook a small shop vacuum to the cabinet to pull out that dust. You'll also need a filtered inlet to allow air in for the vacuum.

  20. #20
    Advisor
    Join Date
    Mar 2008
    Location
    Central New Jersey
    Posts
    544
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    I'm not sure the hp/cfm/psi you'll need but tank capacity is very important. I'm not sure if anything under 5hp is suitable.

  21. #21
    Member brokencase's Avatar
    Join Date
    Feb 2011
    Location
    Pennsylvannia
    My Bikes
    Scott CR1, Dawes SST-AL
    Posts
    44
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Smithie,

    It is much easier to use paint stripper to get the paint off of these frames.

    Abrasives on power tools or naval jelly can be used to remove any rust.
    You can even do electrolytic rust removal :
    http://www.rowand.net/Shop/Tools/Electrolysis.htm

    You will need at least 4hp compressor running on a 220V circuit to do sandblasting.
    Even with this is it is still faster to use paint stripper.

    For as often as you plan to do this I just don't think it's worth the trouble.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •