aluminium oxide

[rtbcomp]

Yes glass & beads are completely different. In my opinion glass grit is better than J-Blast (the most popular expendable media), it can be used at slightly lower pressure and although expendable will keep on working until it disappears as dust in your filters, albeit at reduced efficiency. The biggest problem with worn grit is that it tends to stick in the pot so you get uneven feeding.

I use worn grit to blast scooter engine casings then finish them off with beads. New grit may tend to embed.

That said, you'll still have difficulty with modern alloys, I've not tried new grit on them as I have been told that the resulting surface is too rough, although the finer grades may be OK?

 

[mike k]

Would you say it's removal capability is comparable to aluminium oxide? After removing the coating of say a wheel by blasting as opposed to chemical removal, followed by outgasing the wheel will require blasting again anyway so if the surface is too rough off the glass grit I could re blast with ao to achieve the desirable profile. With glass grit being so cheap I wouldn't be bothered about recycling it, it would be the grafter with bead and ao being used for cleaning and profile.

 

[rtbcomp]

I've never tried AO so I couldn't say.

I'm about to blast some aluminium with new grit later today so I'll get back.

 

[mike k]

Let me know how you get on. I was doing a lot of reading up on the glass grit last night, the general concensus was it leaves a good profile for coating, it cuts through coatings well and embeds itself less than ao and is favoured in many industries for that reason. It is considered a one shot deal but like you do it can be reclaimed until it's all turned to dust. The big plus is its cheap to dispose of as it's not considered hazardous waste like ao and other mineral based media. Really appreciate the heads up on glass grit, that's what i am going to try. I will have to use the finer stuff as i use a 2.5mm nozzle, need to get a sample bag now to try.

mike

 

[mike k]

Sorry to go off topic slightly..
Would glass be ok for a 2.5mm pressure pot nozzle?

Please accept my apologies for saying you would have no problems as I didn't realise there was a difference between glass beads and grit. If you were referring to beads then no problem but with the grit it would depend on the grade as some of the coarser grades have particles bigger than 2.5mm. I have the same size nozzle as you so I will have to try the finer grades.

mike

 

[rtbcomp]

I'm using Stacey's fine grade with a 2.5mm nozzle ok.

Bear in mind that one firm's description of grades may differ from another's.

 

[mike k]

I was looking at partical size as that seems the way the glass is graded by all the suppliers I've seen, not in grit as I'm used too. I think the coarse stuff would be too rough a finish for what most of us would require when you see the partical size.

Rtb, how did you get on today?

Mike

 

[rtbcomp]

The fine I used is 0.2 to 0.7 mm, the next size up, Fine/Medium is 0.2 to 1.5 mm, which I reckon would be too coarse and too big for a 2.5 mm nozzle.

This is an ally casting after blasting with fine glass grit:



And then blasting the same item with glass beads.



The beads were a well worn, but suitable for my purpose.

 

[mike k]

Thanks for uploading the pics, certainly looks comparable in profile to ao and a good surface to coat in the first picture. Had you smoothed off the casting before blasting? Have you used it to remove powder coating? I know you use/used methylene but that's not for mebut being we have a similar set up I was interested to know. Apparently the glass grit is good at cutting through coatings?

Mike

 

[rtbcomp]

The original state of the cover was muddy with a bit of paint on it. They usually come in covered in mud & oil. I just blast them as they are after degreasing.

If any media will remove a coating glass grit will. Some powder coats, especially primers, can be very difficult to blast with any media and chemical stripping is the only viable alternative. This will have to be followed up with light blasting to key the surface.

Avoid holding the nozzle in one place, you must keep it moving otherwise you'll gouge the metal.

I've made a turntable for blasting wheels, makes life much easier.

 

[mike k]

Primers are a nightmare, tried in the past but was using the wrong size nozzle for the FAD CFM available! Didn't know any better then. So i only used blasting for cleaning up parts i had ported or refurbishment of calipers and such like. Now i have all the coating gear, kool koat 3.0dpw and a half decent sized lab oven and spray booth with a teco powered extractor so i will be using the blasting gear a hell of a lot more. Picked up a ace eng 2.5mm tungsten tip too for use with me new pot blaster for good measure. Just sorting out the wiring in the garage now so i can run everything!

What are you doing with the intake manifold - porting, coating or both?

mike

 

[rtbcomp]

What are you doing with the intake manifold - porting, coating or both? mike

I just clean the mess off - the owner does all the complicated stuff.

 

[mike k]

I've made a turntable for blasting wheels, makes life much easier.

any chance of a pic of your turntable? Or what you used to make it?

Much appreciated

mike

 

[rtbcomp]

Basically it's a Rover Metro rear hub with a front disc mounted the wrong way round on top of the existing drum. The hub is fixed to a stand such that a wheel will not rub on the bench.

With hindsight I should have retained the brakes, as it starts spinning once you begin blasting a wheel!

 

[brightspark]

Basically it's a Rover Metro rear hub with a front disc mounted the wrong way round on top of the existing drum. The hub is fixed to a stand such that a wheel will not rub on the bench.

With hindsight I should have retained the brakes, as it starts spinning once you begin blasting a wheel!

use it to your advantage then if it spins freely . just tilt your jet slightly and it will turn slowly and theres no need to move your jet round

 

[rtbcomp]

It spins too quickly and the jet angle required to prevent it spinning isn't always the optimum for removing rust and paint.

 

[mike k]

Basically it's a Rover Metro rear hub with a front disc mounted the wrong way round on top of the existing drum. The hub is fixed to a stand such that a wheel will not rub on the bench.

With hindsight I should have retained the brakes, as it starts spinning once you begin blasting

Thank you kindly, the hub won't be ideal for me but you have got me thinking

mike