14 replies to this topic

[Matt]

Hey everybody. Just wondering if anyone could tell me what fittings are needed for making up crossette pumps. Or if none are even needed at all, I'm just considering making a crossette pump. I have nothing to break crossettes with but it would be nice to know that I own a pump

-Matt

[bernie]

First I want to wish a happy birthday to you Matt. Hope you had/have a great one!

I was never able to figure out how to make a crosette pump with just a lathe. Your most likely going to need a milling machine to make that four pointed star cavity. Give it a whirl if you have access. I bought mine from R.Wolter.

Do you have dimensions to work from or would you like me to put the calipers to the ones I have and work from there?

You might want to try making a simple cavity pump first for the experience.

If R. Johnson is looking he can be of excellent help I'm sure.

[Matt]

Cheers Bernie. I did have a pretty entertaining day.

I am planning to use our milling machine. I had asked my dad a while back wether it was possible to mill up a crossette pump (I showed hime a picture of one) and he just said you would probably need a fitting for the job, could have just been trying to get me to piss off though haha. What size comets does yours turn out Bernie?

-Matt

[bernie]

I propose we work off the dimensions of a 3/4" pump. You can scale up the proportions if you need too. It's cheaper to screw up 3/4" stock. Anything smaller seems like it would be tedious. Aluminum would be my choice. Workable but fairly hard. Can you get the tubing for the cylinder? I want to say 6061. Ask your pop about Al.
***** *****
Just went over to Wolters site and he lists pumps as small as 3/8"! How the heck do these guys do this stuff. Wizbangs I tells ya.

The smaller pump that I have made by Rich produces 1 1/8" comets. It appears to me that the nib or protrusion which forms the actual cavity is turned on a lathe then chucked or clamped in a milling machine to cut the star. Your going to need to index those four cuts 90 degrees from one another so they are uniform. That cavity forming protrusion is tapered while on the lathe approx. 5 degrees so the comets slip off more easily. I don't think I would skip that step.

The milling aspect that forms the star shape does not appear to be tapered.

A nice feature is the 1/8" step on the piston to accomodate a cardboard disc. There's also a roll pin inserted into the piston that is used for the stop against slot that is milled into the cylinder sleeve. Last but not least is the small pin that extends beyond the protrusion. That's your fuse hole. Bore a hole to accept a 1/8" s.s. pin. It sticks out 1/4", 3/8"max.

Am unable to find that 3/4" version just now but would be happy to list the specs. for the one mentioned above. Let me know.

Edited by bernie, 16 December 2003 - 03:22 AM.

[Matt]

Hmmm, Well it sounds a heck of a lot easier now that I know the star isnt tapered aswell. That part would have been a bit more fiddly. It all seems relaively straight forward really. Im guessing I would just need a smaller cutting peice than whats one it now.... unless thats how big they all are. I might give it a shot tommorow after I knock off. Metal and whatnot is not an issue really, we have plenty to work woth even just using cut-offs from previous work.
Cheers Bernie, your always there to help.

-Matt

[bernie]

Need more specs Matt? Better hurry, this pc is about to blow a cathode tube I think. Merry Christmas to you guys just in case.

[Matt]

Nah thats plenty to work on. Now I just gotta find time to do it when my dad is around. Gotta get him to show me how to work te beast.

-Matt

[bernie]

Have fun Matt. Finish it at smoothly as possible. Little machined ridges will cause problems with the extraction of the comet.

[Mortartube]

Have you been here? It may help.

http://www.wecreate4...omet/comet.html

[alany]

It shouldn't be too hard to make it with a dremel style tool.

Just rough cut a dowel with a small tenon saw to establish the square tapering sides, then use the sanding bit on the rotary tool to curve the surface between the four points.

I've actually been looking at making a crossette pump myself. I was thinking of making it using a cylinder core and thin pieces of metal for the break plane gores. You could cut up two pieces of some thin Aluminium sheet, notch them so they can cross in the middle, and then press them into a cross-cut in end end of the core. Coat with epoxy who's surface tension should form fillets.

There is also no reason why the gores need radiate from the core out, you could probably notch the side of a cylinderical comet carefully with a scrap of hacksaw blade, then drill a central hole and a smaller coaxial hole for the flash hole. Lots of work for making many crossettes, but a way to make just one or two for testing.

I am pretty tempted to just buy one from Wolter though, all nicely coated, but expensive.

[Matt]

Alan! good to see ya made it. Your now the third aussy

I think to myself if I have a dremel and a milling machine.... why would I choose a dremel. Ive decided that crossetes really arent on the top of my priorities at the moment, I just recieved a kilo of -325 mesh spher Al the other day so ive been fiddling with stars and sparklers. I thought I had made a batch of glitter stars by accident but I think they just arent dry yet

-Matt

[alany]

Yeah just got my account today, yay a Christmas present. :-)

I didn't realise you had (access to)? a milling machine. Your Dad's a metal guy isn't he?

Did you get the spherical from him or MPA?

I've also got 1 kg of spherical Al, it is great in glitter, but it useless in flash, and not all that good in Al streamer stars, at least not without BaNO3 or KClO4. I really love my spherical Titanium though, it makes wonderful gerbs and drivers, and although a bit pricy its great in stars too.

[Rhodri]

Hi Alany

Would you care to share you formula for streamer and / or stars in general?

If so there's a topic started somehwere which you can append.

I LOVE stars!

[alany]

I actually just headed over to the star comp thread and made a post before I read this. :-)

[Rhodri]

Maybe the forum is based on 'time fuse'?



Highly informative website - GOOD STUFF!

Edited by Rhodri, 24 December 2003 - 06:13 PM.