How to sandblast stainless dowels 1/32 dia x 1/2"?

[scottm]

Any thoughts? If they weren't 304/18-8 stainless I'd use a magnet. They fall through a screen, will probably blow all over if I don't hold onto them. I'm going to try sticking them to duct tape, but have to be careful I don't get chunks of duct tape in the sand.

 

[KLF]

Can't you just buy new ones?

Hold on to them with pliers? Vice grips?

 

[HIKCM]

Drill holes into a 2x4 or other piece of wood, insert the dowels and blast away... Flip the dowels to blast the other end!

 

[HIKCM]

Gottah add use very fine sand and the smallest nozzle you can use on your sand blasting unit!

 

[scottm]

Tape left them sticky, kinda tedious for 50-100 dowels. They also bent from the heat, and I went lightly on them, argh.

I need them roughed up to simulate the needles a customer needs me to build a machine to process. The needles are grit-blasted so glue can hold them in a plastic part. Singulating them can be tricky. A tooth-pick dispenser does a good job, but you never know when a particular material will jamb-up instead of flowing nicely in the bottom of a hopper. Before I quote this job, I need to do some tests to see how this will work.

Holes are a good idea, a lot of holes. Maybe in some nylon or Delrin, we don't have much wood in the shop, and I don't want wood chunks in the blaster.

 

[Photoman]

Do you think tumbling would work? I know something like brown pyramids in a vibratory tumbler will rough things up a bit. If you don't have a tumbler maybe put them in a container with media and spin them on the lathe or even a drill?

 

[Pin_Head]

Use them dirty.
They are so tiny it won't matter.

If they really are 304, you could passivate them in nitric acid. That will also take anything that is not stainless off them.

 

[scottm]

These are really the size of short needles, tough to put them in a lathe or drill. Tumbling them might work if I had a tumbler, although sifting them out of the media would be tough, they fall right through window screen.

My prototype for testing, the pins will go in the chute in the middle, down the slot, and hopefully fall into grooves in the 1/2x1/2 steel on the bottom as it slides through. I used a thin bandsaw to cut this groove but it's slightly crooked. I'll have someone EDM wire-burn some proper notches in it tomorrow. It's been suggested I'll need a vibrator to keep the pins flowing, but the pins at the bottom of the slot should get bounced around as the slot goes by. I'll rake the bottom slots across and back each cycle, two chances for a pin to fall into the slot.

 

[2mbb]

can't you ask your customer to supply you with the needles he will be using? What ever you do may not be the same as what the customer has.

 

[scottm]

My customer's customer will be supplying unsharpened pins for developing and testing, eventually. I'm just not very busy and trying to get ahead of competitors and help out my customer.

 

[Waorani]

Until I saw/actually thought about the size I would have said dump in a sieve and lightly blast while shaking (possible you can find a small enough mesh sieve?). Otherwise dump them in a small heavy mil Ziploc with some decent media and rub away/carry around in your pocket for a few days.

 

[LDowney]

Could you use a tumbler (vibrator) like you would use to clean brass for cartridge re-loading? The media may need to be more abbrasive than what is normally used with such a tumbler (sorry, I am probably using the correct terminology for this equipment).

Good luck