Building a blasting pot.

[Curious]

Hello guys,

Im new to this forum and have spent a couple of evenings trying to establish a spec for a blasting pot I want to build, Ive read lots of threads on here but still a little unsure. My reason for build rather than buy is I have the skills and equipment to make a good job and Im lead to believe that the cheap ebay or Machine Mart pots all benefit from some improvements anyway so if Im going to tinker I might as well tinker properly!

Ive got a 15kg Butane pot so thats my starting point.

Firstly, I have a 3hp 150L 13CFM compressor which seems quite small for blasting and would limit me to a 3mm nozzle or so Ive read?. I have an option to buy another compressor of the same size, will running two in tandem make a noticeable difference, if so in what way?

Will two tougher shift rust and paint faster or will they just have to work less than one? not really sure how two will be better than one?

Onto the pot, for the air inlet into the pot and then down to the media valve should I run 1/2BSP fitting or bigger/smaller?

I saw a grit valve thread that looks interesting and would be easy enough to make.

Any suggestions on what to expect from my compressor set-up or advice on my blasting pot build would be gratefully received.

 

[Dcal]

Hi and welcome to the forum.

The cheap blast pots are a very simple design and the only reason to buy instead of building one from scratch is they are just so cheap it's not worth the bother.
However, this is a diy forum so making stuff is the point and if you have the time, the skills and the kit just get stuck in.

@brightspark has built a few and his media valve is a great addition to the setup.
I made a version of his media valve that has preformed faultlessly but his is a tried and tested design.
The tungsten nozzles are also pretty much a must have.

A 3hp compressor will not have enough air for even a 3mm nozzle.
Two 3hp will be just about enough.
Having two will mean you don't have to keep stopping to let the air supply catch up and will work better because the air pressure will be maintained at a higher pressure which will improve the performance of the blaster.
Keep the airlines and fittings a reasonable size but there is no need to go overboard, 1/2" or 3/8" will work fine for the blast pot.

Apart from that be careful of the build and the welding.
They are a pressure vessel and if shoddily built can be a potential bomb and if they let go they could cause serious injury

Having said that you really need to mess up and they are easy to pressure test.

Good luck and please put up a build thread.

 

[Curious]

Thanks for the welcome Dcal, I followed one of your builds the other night and your interpretation of the media valve, glad to hear its working well.

The only reason I thought about building was it seems the ebay pots need a lot of work and starting from a calorie bottle didnt really seem much more work. I would have no problem buying a cheap ebay pot if it was thought to be the best/easiest route to go?

Other that increasing the pipework size, improving the media valve and fitting a tungsten nozzle is that pretty much it?

I did consider buying one of the cheap cabinets and doing the work on that with a media valve and making the cabinet pressurised as I dont know how much mess working outdoors on small car parts will be?

 

[Dcal]

Thanks for the welcome Dcal, I followed one of your builds the other night and your interpretation of the media valve, glad to hear its working well.

The only reason I thought about building was it seems the ebay pots need a lot of work and starting from a calorie bottle didnt really seem much more work. I would have no problem buying a cheap ebay pot if it was thought to be the best/easiest route to go?

Other that increasing the pipework size, improving the media valve and fitting a tungsten nozzle is that pretty much it?

I did consider buying one of the cheap cabinets and doing the work on that with a media valve and making the cabinet pressurised as I dont know how much mess working outdoors on small car parts will be?

The mods you listed will make a vast improvement on the cheap blast pots and make it a very useful tool.
It can become a bit crazy and there are lots of mod that you can do but you have the main ones covered.
A foot valve to turn the air to the pot on and off is a nice option that I have added and having a bigger opening for filling is a big help but watch how that works because if it comes off it will take your head off. So design it fail safe so that you can't open it under pressure. (think inspection covers on the old air receivers)

I would consider getting a cabinet for small parts and pipe the pressure pot blast pipe into it, (it's what I've done) for the bigger stuff I just blast inside a bit of a tent to contain the grit which get everywhere. If you live close to people you are asking for bother.
If you get a cabinet you will need dust extraction or you will not be able to see anything.
I started a thread on the mods I did on mine but it got a bit OTT (it does work great now though)