pudidotdk Posted March 10, 2007 Posted March 10, 2007 I love the crossette effect, but since I can't get my fingers in those sexy pumps I'll have to make them myself.I'm thinking about a 20 mm pump, very primitive. I made one the other day containing a pump and a cross former, I only got 1 out of 11 exploding (not sure if it went in 4 parts), but that was because the flash powder was different from the other. Does anyone know the proportions/dimensions for crossette pumps? I've seen a little on different sites but that not enough...
pudidotdk Posted March 12, 2007 Author Posted March 12, 2007 Since I got no answers I decides to make a quick and primitive one. Its a bolt with a cavityformer of wood. The pin is a knitting needle that is lathed with a pillar drill. Pump:http://img365.imageshack.us/img365/9302/dsc01263ms6.th.jpg Dirty cavity former:http://img373.imageshack.us/img373/3715/dsc01265lz3.th.jpg Ramming:http://img296.imageshack.us/img296/8020/dsc01271xq6.th.jpg Crossettes (hopefully!):http://img155.imageshack.us/img155/1624/dsc01272aj9.th.jpg If any of you have some dimensions or proportions, please tell! I'd like to make a pump in alu.
Mumbles Posted March 12, 2007 Posted March 12, 2007 The cavity looks awefully fat. Here are some dimensions someone gave to me. For my 3/4'' pumps with a cylindrical cavity:Length of Cavity: 15mmDiameter of Cavity: 9mm tapering to 7mmLength of timing pin: 6mmDiameter of timing pin: 2mmDistance from tip of pin to bottom of crossette (ie. burn distance to flash): 10mm
Wyvern Posted March 12, 2007 Posted March 12, 2007 While were on the subject of crosettes what glue do you guys use for gluing the end disks on? and what material do you use for the end disks?
pudidotdk Posted March 12, 2007 Author Posted March 12, 2007 Thanks mumbles. The place for the enddisks might make the cavity look fat, i don't know. Anyways... -does anyone have dimensions for cross-shaped?I might consider making both cylendrical and cross shaped cavity pumps to see what works the best for me. -Does anyone have some decent composition for both crossette and breaks? Have read a lot, but new compositions would be cool.
Wyvern Posted March 12, 2007 Posted March 12, 2007 I have used this formula which i modified from Win 39 glitter Potassium Nitrate 51 Charcoal Airfloat 15 Antimony Trisulfide - 400 mesh 12 Aluminum, atomised 10 Ferro-Titanium 40-100 mesh 7Sodium bicarbonate 5Dextrin 5% which gives this effect http://tompearceltd.co.uk/W39.wmv
Mumbles Posted March 12, 2007 Posted March 12, 2007 I thought the dimensions I gave were for a cruciform, I see that is not the case. Perhaps just making the diameters the lengths of the sides will do the trick. The cross does taper from top to bottom. The square cross-section of the top is larger than that of the bottom. Just a few things I've noticed about your tooling. The lower pin for passing of fire looks pretty wide. This makes me think you'll probably have to use rolled shots. Otherwise you'll get a lot of jetting. Jetting occurs when the bottom or top of the crossette breaks out instead of the sides. Rich Wolter changed his design somewhat, which it seems you are trying to recreate. I've used both sets actually. The new design is cleaner in the manufacture, but I haven't gotten a chance to test them yet. The new design has a longer passfire pin. I've heard sharpening the tip of this makes the crossettes work even better. The sides of the cruciform are also tapered in the new design. It used to be that the cruciform had sharp edges the entire way up. Now it goes from a point at the bottom, and the groove is the same diameter the entire way across. This forms a triangle like shape on the sides. It also aids in getting the pump out. Might help the break too. He also removed the so-called enddisk cavity. It is now almost completely flat. Reguardless of this I've always used end disks that covered the entire top of the crossettes. End disks are made from a thicker poster board. Theres one that is that is about the thickness of manilla folder paper, and there is one type that is thicker. I use the thicker, but not that foam core stuff. Something like a cereal or soda box will do. They are cut with an arch punch I've also made mainly win 39 crossettes. For the burst you are going to have to experiement. It all depends on the tooling, size, and fusing used. Whistle, 70/30, 1:1 granulated BP:flash, and dark flash are the most commonly used materials. Mg flash is oftentimes suggested for very small crossettes. Many try to shy away from Mg flash and 70/30 as it can bleach your retinas and make charcoal and other low light comets look worse. A BP-flash mix inexplicably doesn't provide nearly as much light. You will also have to experiment with fusing. Thermalite works the best, but it is pretty hard to get. Chinese paper fuse is also used fairly often. Fast visco is also gaining in popularity. No fuse is of course simpler, but harder to get to work as well.
Wyvern Posted March 14, 2007 Posted March 14, 2007 I've been trying dark flash with my crosettes 1:1 perc:Sb2S3 but the glue holding the end cap on itsnt strong enough i think, can you recommend any one in perticular?
Frozentech Posted March 14, 2007 Posted March 14, 2007 I've been trying dark flash with my crosettes 1:1 perc:Sb2S3 but the glue holding the end cap on itsnt strong enough i think, can you recommend any one in perticular? I've found that even using dark flash, I needed to make rolled shots to achieve 100% reliable breaks on 3/4" crossette comets. I use hot glue, applied around the edge of the cover disk. Are yours jetting ?
Wyvern Posted March 15, 2007 Posted March 15, 2007 They're not so much jetting than blowing the disk off the top
Mumbles Posted March 15, 2007 Posted March 15, 2007 How thick are your end disks, what are you using as a glue, and what are you using to cover the sides of your crossettes?
Frozentech Posted March 15, 2007 Posted March 15, 2007 They're not so much jetting than blowing the disk off the top Hmmm.... never even heard of that happening. Do you have video of some stargun tests ? It seems odd because if there is enough confinement to blow an end disk off, but NOT break the crossette, pressure would definitely blow out the burnt through pinhole ? Some construction pics and a video of a stargun test might help diagnose this.
Wyvern Posted March 15, 2007 Posted March 15, 2007 Im using 3mm thick cardboard disks which i make myself with layers of wallpaper backing and Pva which set rock solid and using pva (as per the passfire tutorial) to secure it over the cavity. and im using 3 turns of 70lb kraft around them.
cplmac Posted March 15, 2007 Posted March 15, 2007 You can get away with just a couple as in two turns of masking tape around the sides, it's really just there to keep the fire from riding up the sides. I hot glue my endcaps on and they never blow off, of course I also fold the masking tape from the sides over the top disk.
victor Posted March 16, 2007 Posted March 16, 2007 There is a crossette technical article on our website, perhaps you can view it. The URL is: http://www.fireworkstown.com/NewsDtls.asp?Id=2074
Mumbles Posted March 16, 2007 Posted March 16, 2007 Victor, just be aware that I'm not going to put up with you like they do at the UK Pyro society forum. All you do is plug your site and ask which of your products they like better. If you want to be helpful fine, but if you begin to start tons of useless topics, I'm going to ban you.
Givat Posted March 16, 2007 Posted March 16, 2007 Link doesn't work.By the way, some maybe bought crossettes tools and can measure their diamentions.
pudidotdk Posted March 16, 2007 Author Posted March 16, 2007 Link doesn't work.By the way, some maybe bought crossettes tools and can measure their diamentions. That would great!
victor Posted March 17, 2007 Posted March 17, 2007 Victor, just be aware that I'm not going to put up with you like they do at the UK Pyro society forum. All you do is plug your site and ask which of your products they like better. If you want to be helpful fine, but if you begin to start tons of useless topics, I'm going to ban you.Mumbles, I am so sorry if caused you any antipathy. I really don't want to give you all such a bad impression, I don't mean to make advertisement our website directly in the forums. I am not sure which kind of role I should act will be right in this forum, and I am tring to find a way which you all can accept to do. By the way, can I save my signature? Thank you
Mumbles Posted March 18, 2007 Posted March 18, 2007 Alright I got a pair of calipers out and measured up my 3/4" pump. All measurements are in mm. The former at widest and narrowest are the side lengths if it were a square, but it is of course a cruciform. The interior measurements are on the indents of the cruciform. pump diameter 18.90mmpin diameter 2.50mmPin length 5.20 mmformer at widest 8.00mmFormer at narrowest 6.35mmInterior at widest 6.35mmInterior at narrowest 4.8mm
Mumbles Posted March 19, 2007 Posted March 19, 2007 I knew I forgot to measure something. Assuming a 5 degree taper, the length is 18.5mm, which seems about right. I think it was about as long as the press is wide. I'll measure next time I get home, but if someone else has a 3/4" pump, they could measure up.
cplmac Posted March 20, 2007 Posted March 20, 2007 I just threw the digital caliper on mine and it read .6" from the base to the end of the cruciform, and .8" from the base to the tip of the fuse pin.
pudidotdk Posted April 15, 2007 Author Posted April 15, 2007 Okay, I'm going to make an order on a 14 mm and a 30 mm crosette pump through supremepyro so i guess i don't have to make one myself. But does anyone have experience with 14mm. I guess this takes a pretty hard flashpowder to break? What flash powder do you think might be needed?
Mumbles Posted April 15, 2007 Posted April 15, 2007 The sheet that comes with the Wolter crossette pumps recomends Mg based flash powder for smaller ones. I'm guessing it will take a pretty strong flash powder to break the 1/2" ones.
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