Blasting grit

[Ianbuckwell]

hi, wasn't really sure on which forum this should go in, but I was wondering if anyone local to lymington Hampshire either had some spare blasting grit I could buy a smallish (10-25kg) bag of or if there are any local suppliers or blasters likely to sell me a bag locally? For the quantity I am after postage costs more than the grit!!

The reason I am after a small amount is because I am making a diy pot blaster and don't want 1/2 ton of grit to only find it doesn't work very well.

I realise using sand is a big no no, but if I were to test it with sand I assume it has to be bone dry, but should it be fine paving sand or courser building sand that I have dried?

Sorry for all the questions, but one last thing what do you guys use as nozzles, airline pipe fittings, or ceramic from spark plugs etc? If spark plugs how do you get the center electrodes removed?

Many thanks.

 

[rtbcomp]

Welcome to the Forum, I've moved this to the correct spot.

Re sand, it's illegal to use dry block paving sand in blasting on business premises, even though some people swear by it, others say it's not that good. Building sand is even worse because it contains bits that need sieving out. It also takes a lot of drying.

Re nozzles. It depends on how much air you've got, I use tungsten carbide nozzles as they're best in the long run. 2.5mm is OK for a 14cfm compressor. To experiment with drill a 2.5mm hole down the middle of a bolt, it won't last very long, but at least you'll get the idea.

 

[ben8vgte]

I have just built one myself, I'm using a 2.5mm nozzle off ebay from Ace car parts with a single 14cfm or so cfm compressor. It does work well enough, but I do have a 2nd compressor to plumb in ad will use a bigger nozzle then.

I did get some 30-60 Garnet grit from work, but was perhaps a little to big for the small nozzle to work well. In the end I started using the old fine grit after it's been round the one at work a few times and that works well, might be around 120-240 grit at a guess.

 

[rtbcomp]

J-Blast Supafine is the usual general purpose grit for a 2.5mm nozzle.

 

[Ianbuckwell]

Thanks for the help guys, and sorry for posting in wrong section. I about the health risks of using sand and would not intend to use it permanenetly , it was more a test to see if my build works.

Do you diyers purchase the correct blast hose or do you just use some think walled rubber hose etc? I like the idea of having a shut off valve on the end of the hose for convenience but think this should only be done if the correct blast hose is being used, don't really fancy a face full of sand and pressurized air!

 

[Ianbuckwell]

Ben8vgte - just searched your thread, you are a bit of a whizz! Do the blast nozzles fit standard plumbing compression fittings or is it a specific brass part? Also if you don't mind what are the chain wheels used for, are they just a handle/extension to easeaccessfor adjustment?

Last question (for now ) I am have a 100l 2.5hp compressor and a plumbed in approx 100l gas tank, although ultimately my air supply is insufficient for long term use. As I intend to only do very small parts (1in sq. total area on car to remove stone chip rust completely as I read its the only way to do it) I am using 1/2bsp tee on bottom of tank where air/grit combine, is this too big? Sur edit won't, but I have visions of the air speed being too low and the sand just dropping out of the air, will it be OK?


What grit is good on remove paint remnants and mainly miniscule rust particulars from any pores/pits in the steel? I assume it is also a question of air adjustment.

My car is my love (one of them) and I am terrified of screwing it up, but at the sometime I don't trust a body shop to charge me the priviledge of screwing it up for an atrocious sum!!!!

How/what is used to mask areas close to repair to stop direct hits from grit and ricocheting particles.


Thanks for the welcome, only just signed up, but been a huge fan of the site for ages.

What is used to mask areas

 

[rtbcomp]

Any hose will eventually wear. Proper blast hose is thick walled and anti-static, I'm using 3/4 inch bore heater hose at the moment because I had a load given to me. This is lasting well because the grit travels more slowly through the large bore.

Try to keep the hose straight, it will wear through at the bends first.

As I said before, J-Blast Supafine is the grit to use. If you work in a cabinet or blast room you can sweep it up, sieve it and use it again, it will last about 3 times, getting finer each time.

I've got a 3/8 tee on my pot, I'm thinking of changing to 1/2 as the hose coupling I use is 1/2 inch.

 

[ben8vgte]

Ben8vgte - just searched your thread, you are a bit of a whizz! Do the blast nozzles fit standard plumbing compression fittings or is it a specific brass part? Also if you don't mind what are the chain wheels used for, are they just a handle/extension to easeaccessfor adjustment?

Last question (for now ) I am have a 100l 2.5hp compressor and a plumbed in approx 100l gas tank, although ultimately my air supply is insufficient for long term use. As I intend to only do very small parts (1in sq. total area on car to remove stone chip rust completely as I read its the only way to do it) I am using 1/2bsp tee on bottom of tank where air/grit combine, is this too big? Sur edit won't, but I have visions of the air speed being too low and the sand just dropping out of the air, will it be OK?


What grit is good on remove paint remnants and mainly miniscule rust particulars from any pores/pits in the steel? I assume it is also a question of air adjustment.

My car is my love (one of them) and I am terrified of screwing it up, but at the sometime I don't trust a body shop to charge me the priviledge of screwing it up for an atrocious sum!!!!

How/what is used to mask areas close to repair to stop direct hits from grit and ricocheting particles.


Thanks for the welcome, only just signed up, but been a huge fan of the site for ages.

What is used to mask areas

Thanks But I'm really not a whizz, there are many on here who know far more than me about blasting. The plumbing fittings were standard I think, just out of magic box of stuff though the idea was from thread on here somewhere. It's worth a search as there is some interesting threads, also on www.homemadetools.net

The chainwheel was just what I had to hand to add on to make my homemade grit valve easy to use.

When I have had to mask stuff at work for the cab I've just used gaffa tape.

I used 1/2" bsp as well, 2 reasons it's what I had to hand (free) and I wanted the option to run it on a big diesel compressor with a decent size nozzle should one come up at the correct price..

Mine has proper Clemco blast hose on, with 3/4" bore it is a little big really for this size pot and air supply. But was free (you can see a pattern forming here) from a line at work that wore out on a bend and burst, though the rest was fine so it went home with me.

For you I'd be tempted to make a spot blast attachment to go over your nozzle, just a plastic box of some kind really. Then connect it to a old vac to save mess, I'm not sure how well it would work but might be worth a go perhaps?

I will say getting the mix between the air and grit flow is quite important, too much grit and you loose speed, too little and not much happens!

 

[Ianbuckwell]

Thanks for the tips, you seem lucky with your free stuff! I have had to buy various fittings etc and sometimes wonder if it would have been cheaper to get a Chinese £90 one off ebay, but where is the fun in that and hopefully mine will be better quality.

As for the shield ai assume you mean an attachment similar to the handheld spot boasters by draper etc that include plastic surrounds to try and contain the grit.

My priority job at the moment would probably been done with a £30 spot blaster, but hopefully if it all works my dad is restoring an MB Trac and it will hopefully come in useful for that.

Thanks.


Anyone know any friendly blast companies/individuals in Lymington/new forest who may be will to sell me a bag of grit?

 

[rtbcomp]

Once I stopped off where a house was being blasted and asked them if I could have the used grit if I swept it up, they thought it was Christmas! They even gave me some new bags of grit.

 

[ben8vgte]

Yeah we just chuck our used grit in the bin (if I don't take it home first) maybe try a local wheel refurb place.

 

[gulf]

Single bags of crushed glass are available on eB*Y in various grit to suit your compressor and nozzle diameter,we buy it in bulk at £80 per ton,so Id imagine if youre only needing one 2o kg bag it wont break the bank even with postage.

 

[Ianbuckwell]

You don't know how small my bank account is


I am going to read up on this, but what is a good allround media and also what is good for remove small areas of mainly surface corrosion from car panels? Guess I am needing something g that is foreground free to reduce risk of futures corrosion?


Does anyone know a good source for shortish (2-3m) of blast hose, guessing I should go for 1/2"?

Thanks

 

[brightspark]

You don't know how small my bank account is


I am going to read up on this, but what is a good allround media and also what is good for remove small areas of mainly surface corrosion from car panels? Guess I am needing something g that is foreground free to reduce risk of futures corrosion?


Does anyone know a good source for shortish (2-3m) of blast hose, guessing I should go for 1/2"?

Thanks

u can run 90cfm on a half inch bore blast pipe with a 6mm jet

 

[Ianbuckwell]

I only figured 1/2" as that is what much of the listed blast hoses start at?
Will using 1/2" on my blast pot pipe work cause the airspeed to bee too low and allow the grit to drop out of the air, if you see what I mean.

 

[brightspark]

I only figured 1/2" as that is what much of the listed blast hoses start at?
Will using 1/2" on my blast pot pipe work cause the airspeed to bee too low and allow the grit to drop out of the air, if you see what I mean.

if your using a 3MM nozzle and a 14cfm comp u need a 10mm bore hose this will give the grit a higher velocity down the hose . using a larger bore will make the grit bounce all over and loose speed

 

[rtbcomp]

I use a 3/4 inch bore hose with no problems, down to 40psi.

In fact the larger bore wears more slowly than a narrow one.

 

[brightspark]

I use a 3/4 inch bore hose with no problems, down to 40psi.

In fact the larger bore wears more slowly than a narrow one.

it will do as the media will be traveling down the hose slower so it wont be as eficient at a higher pressure

 

[rtbcomp]

But it speeds up when it leaves the jet, as the speed of the air & grit mixture when it hits the workpiece is a function of the jet size, not the bore of the hose.

In fact efficiency will be increased as the larger bore hose will offer less resistance to the airflow.

 

[brightspark]

But it speeds up when it leaves the jet, as the speed of the air & grit mixture when it hits the workpiece is a function of the jet size, not the bore of the hose.

the bore of the hose does matter as said too large and the grit can bounce about in the hose and looses speed a smaller bore hose speeds the velocity of the grit up before it passes through the jet just the same as water does through pipes why do u think ace grit blasters use 10mm bore hose for 14cfm comp and a hodge clemco minipot uses half inch bore pipe for a 6mm jet at 90cfm its for the reason i stated . read up on it and it will explain when i was blasting on a regular basis. u could notice the diffrence using a worn blast hose as soon as u fitted a new one .didnt u ever have a peashooter when u were a kid . the pea was nearlly always the corect size for the tube 2 small and it went nowhere http://www.clemcoindustries.com/products_showitem_clemco.php?item_id=23100