BRDM Driver Posted October 16, 2012 Share Posted October 16, 2012 I have see that many people go for either sand blasting or needle guns. What are the pros and cons? I'm guessing sand blasting is quicker but messy with grit getting everywhere, needle gun is much slower. I don't have anywhere undercover to do this, so i'll look at a temporary garage (just a big tent). This will also allow me to re-spray undercover. Does anyone use the 'machine mart' type sand blasters or is it best to get a professional in with the BIG compressor? I have a couple of vehicles to do. Neither have any corrosion, just old flaky paint to get off. One is aluminium armor, the other is steel armor - no sheet metal. Any other advice? Quote Link to comment Share on other sites More sharing options...
griff66 Posted October 17, 2012 Share Posted October 17, 2012 needle gun is way to go! Quote Link to comment Share on other sites More sharing options...
ruggyjohn Posted October 17, 2012 Share Posted October 17, 2012 needle gun is way to go! cant blast alluminium with grit blasting, use plenty of nitromors paint stripper Quote Link to comment Share on other sites More sharing options...
andym Posted October 17, 2012 Share Posted October 17, 2012 I had my Abbot, which is both steel and aluminium, blasted and sprayed by K Blasting from Brixham (who I thoroughly recommend by the way, as they have MVs of their own). It's very messy and I wouldn't suggest doing it to a complete vehicle where the interior is already finished. No matter how well you mask and cover, an amazing amount of grit will still get in. I took a deliberate decision to blast and paint the exterior before starting on the interior as that way the grit that gets inside isn't really an issue. For reference, it took them about four hours to blast the Abbot. For smaller components off the vehicle I use a "Machine Mart" type blasting gun on a compressor, but there's no way it could do the job a proper blasting setup can. You've only got to look at the difference in size of compressor and hose! Andy Quote Link to comment Share on other sites More sharing options...
timbo Posted October 17, 2012 Share Posted October 17, 2012 I have one of the machine mart blast pots which if combined with a big enough compressor is great for small items but would take MONTHS to do a whole vehicle...get a professional in then it will be done in two days! You can use blasting on cvrts - I had my Spartan done earlier this year but you need to be careful and it is VERY messy, despite best efforts it took for ever to get crap out of all the nooks and crannies. I have also seen a very nice Sabre which years after sandblasting still makes horrible grinding noises when turning the turret! Following Jon Pentons approach seems to be the most efficient way ie a big rotary wire brush on an angle grinder. My advice (which isnt necessarily the best I have to say just one angle!) would be to remove whatever you can - decking, bins, smokes etc and have these blasted and primed separately, then block the vehicle up wheels and tracks off and wire brush/ needle gun followed by priming and painting (you need to rejack and move the blocks to get at the covered bits). Then put it all back together and finish it off with a final coat to bring it all together. Or you could do what the army do and employ an old english sheep dog, cover it in green paint and let it roll around on your vehicle a few times... Just keep telling yourself it will be worth it when its done... Cheers Tim Quote Link to comment Share on other sites More sharing options...
utt61 Posted October 17, 2012 Share Posted October 17, 2012 Anyone have any views on the relative merits of dry blasting compared to wet blasting? Apart from the difficulty finding someone who can do wet blasting, the feedback I have had from heritage railway associates is that it is generally superior. Quote Link to comment Share on other sites More sharing options...
timbo Posted October 17, 2012 Share Posted October 17, 2012 Although I've not come across wet blasting before, Ive just read a bit about it and I have to say it looks like it might work very well in MV's as it seems to avoid the sort of messy clean up you get with sand blasting, and to be capable of being used with much more finesse. Would be interested to hear if anybody has used it... Quote Link to comment Share on other sites More sharing options...
BRDM Driver Posted October 17, 2012 Author Share Posted October 17, 2012 I guess dry ice blasting would be the ultimate clean blasting.... Somehow i doubt it would be cheap though! Quote Link to comment Share on other sites More sharing options...
BRDM Driver Posted October 17, 2012 Author Share Posted October 17, 2012 The dry ice blasting machine isn't too expensive, but you need a 55kw compressor :shocked::shocked::shocked: to get enough power into the air blast... Quote Link to comment Share on other sites More sharing options...
Lauren Child Posted October 18, 2012 Share Posted October 18, 2012 (edited) One of my friends had a wet blasting machine. They also used it (without the grit) to wash the cars, machinery etc. A visitor used it to wash her car. The white car went very shiny, but then the windows went misty. I'm told the scream could be heard for quite some distance. She had mistaken the grit trigger for a soap dispensor (as on pressure washers). Remember that wet blasting is done with water. You'll probably get rust, particularly in nooks and crannies. It sounds like there are rust inhibitors but you'd need to look at how effective they are, or sand down before priming. Personally my vote is for needle gunning, but make sure you follow the vibration safety advice and take plenty of breaks. Edited October 18, 2012 by Lauren Child Quote Link to comment Share on other sites More sharing options...
griff66 Posted October 18, 2012 Share Posted October 18, 2012 needle gun= very good ear protection!!! Quote Link to comment Share on other sites More sharing options...
Caddy Posted October 18, 2012 Share Posted October 18, 2012 One of my friends had a wet blasting machine. They also used it (without the grit) to wash the cars, machinery etc. A visitor used it to wash her car. The white car went very shiny, but then the windows went misty. I'm told the scream could be heard for quite some distance. She had mistaken the grit trigger for a soap dispensor (as on pressure washers). Remember that wet blasting is done with water. You'll probably get rust, particularly in nooks and crannies. It sounds like there are rust inhibitors but you'd need to look at how effective they are, or sand down before priming. Personally my vote is for needle gunning, but make sure you follow the vibration safety advice and take plenty of breaks. With the vibration values I recon in a commercial setting you'll have about 2 minutes on before you reach exposure levels. It could be fun hooking up my Hand Arm Vibration Indicator from work to one of the needle guns at Duxford and see how long until it sounds off. (I hate needle guns in case you haven't guessed - not for the task, but the noise!!!!) Quote Link to comment Share on other sites More sharing options...
griff66 Posted October 18, 2012 Share Posted October 18, 2012 all these exposure levels are more related to long term exposure not one person taking paint/ rust off their mv re. needle gun hearing protection earplugs in then ear defenders over the top thick gloves help reduce vibs and keep your hands warm cause the guns run cool with all that air going thru em ! when i restored my ferret machine mart needle gun was a god send ,nitromors and similar horrible stuff. Quote Link to comment Share on other sites More sharing options...
Caddy Posted October 18, 2012 Share Posted October 18, 2012 Quick bit of maths = needle gun ave vibration value = 12.2m/s2 Needle gun max useage in an 8 hour period = 21 minutes Food for thought Quote Link to comment Share on other sites More sharing options...
Tony B Posted October 18, 2012 Share Posted October 18, 2012 Quick bit of maths = needle gun ave vibration value = 12.2m/s2 Needle gun max useage in an 8 hour period = 21 minutes Food for thought Add a good set of anti vibe gloves. Quote Link to comment Share on other sites More sharing options...
Caddy Posted October 18, 2012 Share Posted October 18, 2012 all these exposure levels are more related to long term exposure not one person taking paint/ rust off their mv re. needle gun hearing protection earplugs in then ear defenders over the top thick gloves help reduce vibs and keep your hands warm cause the guns run cool with all that air going thru em ! when i restored my ferret machine mart needle gun was a god send ,nitromors and similar horrible stuff. How do you define long term exposure? Removing the paint from a whole vehicle could be classed as long term. Quote Link to comment Share on other sites More sharing options...
Tony B Posted October 18, 2012 Share Posted October 18, 2012 By the time you feel pins and neddles the vibration exposure is to long. I'm now old enough that exposure to chain sawa and such like is having an effect, arthritis starting. Quote Link to comment Share on other sites More sharing options...
Caddy Posted October 18, 2012 Share Posted October 18, 2012 Add a good set of anti vibe gloves. About as much use as a chocolate fireguard with vibration values of this level - they are not proven to work. Keeping your hands warm has been proven to help. Quote Link to comment Share on other sites More sharing options...
Niels v Posted October 18, 2012 Share Posted October 18, 2012 A good thing with needle guns is that they mostly flake the paint of and dos not give that must dust. But I tend to use a angel grider afterwards in areas with a lot of rust and pitting. But needle guns is only for thick parts like chassis and armour not sheet metal. It is not fun to use a needle gun inside a tank hull... not something you want to do if you have sensitive neighbours. Anglegriders with wire brushes are also good but I find that they give a lot of dust and leaves a very smooth sureface which isnt the best for paint to adhere to. Blasting is good it removes everything and leaves a good surface for paint to adhere. But I only use it on things that is completly taken apart. The dust get in to every corner and crevice. I dont like wet blasting, it removes the paint but leaves surface rust... whats the idear with that... :nut: I like to scrape the paint of with a chisel, the paint flakes of and you can get in to most corners and it is quite.. but it takes a long time to do and is a lot work. Heat can help with easing the paint off. But it is only really good on brittle hard old paint. It is what I have done on my bedford. Quote Link to comment Share on other sites More sharing options...
utt61 Posted October 18, 2012 Share Posted October 18, 2012 ... Remember that wet blasting is done with water. You'll probably get rust, particularly in nooks and crannies. It sounds like there are rust inhibitors but you'd need to look at how effective they are, or sand down before priming. If you're wet blasting it is is essential to use an acid wash prior to priming. The technique I have seen used to great effect is to wet blast, dry thoroughly, brush on a dilute phosphoric acid wash (which is designed for the purpose and easily obtained) and allow to dry, then scotchbrite lightly until grey, then prime and paint. This gives an adhesion which exceeds marine standards. It sounds a lot of work, but is actually less work (and healthier) than needlegunning. The acid wash converts the Fe2O3 (rust) to FeO which is very stable and very hard (which is exactly what the trad rust converter does) and also leaves a very adhesive surface. The only real problem I can see is the difficulty and expense of obtaining the wet blast equipment. Quote Link to comment Share on other sites More sharing options...
griff66 Posted October 18, 2012 Share Posted October 18, 2012 caddy if u are using needle guns with vib levels of 12.3m/s2 no wonder u dont like em! quite easy to find ones that have levels more around 3m/s2 Quote Link to comment Share on other sites More sharing options...
Lauren Child Posted October 18, 2012 Share Posted October 18, 2012 (edited) There's some safety info here on the Trelawny website - http://www.trelawnyspt.com/en/products/low-vibration/ I'm sure you'll have been shown how to use it, but it's worth checking whether it's due to be cleaned/serviced and make sure it's oiled each time it's used. It's also worth checking that the chisel needles aren't going blunt - that seems to make a big difference. I always gave it a good check before use as good practice. A quick check on the HSE website found this - http://www.hse.gov.uk/vibration/hav/readyreckoner.htm - not that at 12m/s2 you go above the daily limit after about an hour. If you're planning on using it for longer it's probably time for an upgrade (and as 12 is within the action zone, its probably worth getting some advice from the safety folks and looking at options to upgrade anyway). Edited October 18, 2012 by Lauren Child Quote Link to comment Share on other sites More sharing options...
timbo Posted October 19, 2012 Share Posted October 19, 2012 I also hadnt realised that different needle profiles were available giving different finishes, for example pointed tips for a rougher surface finish and flatter tips to provide a degree of polish. Good site that Trelawny one.... Quote Link to comment Share on other sites More sharing options...
Caddy Posted October 19, 2012 Share Posted October 19, 2012 caddy if u are using needle guns with vib levels of 12.3m/s2 no wonder u dont like em! quite easy to find ones that have levels more around 3m/s2 Damn right! The problem with volunteering is that invariably the kit available to use isn't the best. 3.2m/s is much better. For a living I operate and manage the use of a fair few different types of powered hand tools. At 34 I've already lost a small amount of sensation in my hands and that was just with chainsaws etc. Quote Link to comment Share on other sites More sharing options...
Lauren Child Posted October 19, 2012 Share Posted October 19, 2012 I also hadnt realised that different needle profiles were available giving different finishes, for example pointed tips for a rougher surface finish and flatter tips to provide a degree of polish. Good site that Trelawny one.... Yep. Remember to test an area as they do leave marks depending on the tip though. The chisel tips seem to work quite well, but you need to keep a stash as they wear blunt. The folks behind that website were quite helpful when I chatted to them and I've used the 2BPG that was good and reliable. I'd be tempted by the lower vibration ones if you were buying new though. Quote Link to comment Share on other sites More sharing options...
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