Fly Posted July 18, 2010 Posted July 18, 2010 Mumbles I have been reading that long, long BP thread.You said you used 10% water when corning.I think maybe that been part of my problem, using to much water.I have just been eye balling it.My question for you is,when you press, how longto you keep it under pressure? I took your tip & made up 15g & added 10% water & pressed.I left the pressure on for about a minute & watched as watercame out around the base.I kept wiping away the water till it no longer came out. It's drying now & I plan to test it in my mortar in the morning. Fly
Ventsi Posted July 18, 2010 Posted July 18, 2010 I don't mean to be a dick, but wouldn't it have been easier to PM him? Anyway about a minute under pressure should be plenty, you'll get complete compaction and not an awful lot of stress on your press. Of course even ten seconds will do.
Fly Posted July 18, 2010 Author Posted July 18, 2010 Thanks Buddy.I guess I could have PM him, but maybe someone else could benefit from this post.That's what this form is about,is it not? Fly
Mumbles Posted July 18, 2010 Posted July 18, 2010 10% seems a little high if you have a good press. Given the fact that water was coming out, you could get away with less if you wanted. I generally just granulate my BP now. If I were pressing, I'd likely now step it back to around 6-8%. With good presses I've heard of people dropping it back to 4%. I generally pressed to a set density when I was doing my experiments. I'd press it and let it dwell for maybe 30 seconds, and then compact again if I needed more pressure. I've seen that done with vices. It's hard to get to the optimal density in one pressing. About 5-10 minutes between twistings helped to get it up to the where we wanted it, which was 1.7g/mL
Fly Posted July 18, 2010 Author Posted July 18, 2010 Mumbles thank you my friend!The SAME BP I have been playing with I just corned as in my post above.I just took it outafter drying & test fired my golf ball in the mortar.MAN I did not time it but I,m ready to test against the Goex. I think my whole deal was to much water.The kno3 was turning crystal on me.Man I feel like I just landed on themoon.I'm not threw testing,but what I have now will work for anything I need. Thanks everyone Fly
Fly Posted July 19, 2010 Author Posted July 19, 2010 Let me add one more thing here.I made a grains measure at 35 grains for my cap & ball revolver.Goex weight is 23g atthat volume.I just checked my bp & it's weight is the same. I have always tested the powder by weight & not density.But that's cool home made can be the same weight & volume. Fly
al93535 Posted July 19, 2010 Posted July 19, 2010 When I press my BP I keep it under pressure for about 3-5 minutes. Then I increase the pressure again seeing as how the powder has compacted. I do this at least three times. Also, for 200 grams of BP I spray 14 sprays of distilled water into the bowl while mixing. Each spray being about 1 milliliter and that being one gram I use about .07% of water. The grains come out hard hard. Its a alot of work to break up the pucks. You sure dont want to use too much water, thats for sure!
Ventsi Posted July 19, 2010 Posted July 19, 2010 just to correct you Al, if each spray is one mL and 1mL=1g then you are using 14g of water per 200g BP, which goes to 7g H2O-100g BP. That leaves you with 7% water.
Fly Posted July 19, 2010 Author Posted July 19, 2010 Al what binder do you use.I did this batch with 4% dextrin.My next I'm going to use 2% red gum
al93535 Posted July 19, 2010 Posted July 19, 2010 Hahahahah yes you are right. 7%! I guess I was thinking multiply by .07 oh well, good catch! I use dextrin, at 4%.
Bonny Posted July 19, 2010 Posted July 19, 2010 I used to press mine with 10% water (no binder). I would have water leaking out, but never had any performance issues. I use a 12 ton jack and press 3" diameter pucks. Now I use ~ 5% water (no binder). I let the press dwell for 5-10 minutes under pressure, then pump it up again. I repeat this one more time and then remove the BP from the press. They have that nice 'clink' sound even when still damp.
LittleOsama Posted July 22, 2010 Posted July 22, 2010 Why in heaven would anyone add binder to corned BP? 5% water is optimum amount, no matter how weak or strong press is.
dagabu Posted July 22, 2010 Posted July 22, 2010 Why in heaven would anyone add binder to corned BP? 5% water is optimum amount, no matter how weak or strong press is. Hmm.... Yes and no. You are looking for a density of 1.7 grams/cc. It will matter a lot if the press is too weak to press it to this density. Yes, 5% sprayed over the top of the heap stirred in as it is sprayed is probably the best method. You are also correct in the fact that you don't need Dextrin for pressing pucks. Here is a TUT on pressing pucks, it can be extrapolated to fit your needs. Lets start with a 1” star press. Lets change this to centimeters, 2.54. Lets find the radius by dividing the diameter (2.54) by 2; a radius is half of the diameter. 2.54/2= 1.27 centimeters Next, lets find the area of the face using the formula: pi (3.1416) multiplied by the square of the radius: 1.27 x 1.27 x 3.1416 = 5.06708664 Lets use the 1” column or 2.54 cm as a benchmark and using the formula of multiplying the height (2.54) by the area of the face (5.07) will give you the volume. 2.54 x 5.07 = 12.87 cc Therefore, if compressed correctly, a 1” x 1” BP puck should weigh 21.88 grams if pressed to a density of 1.7 grams per cc.
dagabu Posted July 22, 2010 Posted July 22, 2010 -or- Lets start with a 3” comet press. Lets change this to centimeters, 7.62 cm. Lets find the radius by dividing the diameter (7.62) by 2; a radius is half of the diameter. 7.62/2= 3.81 centimeters Next, lets find the area of the face using the formula: pi (3.1416) multiplied by the square of the radius: 3.81 x 3.81 x 3.1416 = 45.60 Lets use the 1/4” column or .635 cm as a benchmark and using the formula of multiplying the height (.635) by the area of the face (45.60) will give you the volume. .635 x 45.60 = 28.956 Therefore, if compressed correctly, a 3” x 1/4” BP puck should weigh 28.956 grams if pressed to a density of 1.7 grams per cc.
Bonny Posted July 22, 2010 Posted July 22, 2010 -or- Lets start with a 3” comet press. Lets change this to centimeters, 7.62 cm. Lets find the radius by dividing the diameter (7.62) by 2; a radius is half of the diameter. 7.62/2= 3.81 centimeters Next, lets find the area of the face using the formula: pi (3.1416) multiplied by the square of the radius: 3.81 x 3.81 x 3.1416 = 45.60 Lets use the 1/4” column or .635 cm as a benchmark and using the formula of multiplying the height (.635) by the area of the face (45.60) will give you the volume. .635 x 45.60 = 28.956 Therefore, if compressed correctly, a 3” x 1/4” BP puck should weigh 28.956 grams if pressed to a density of 1.7 grams per cc. I think you missed the last calculation volume of 28.956 cc x 1.7 = 49.225g of BP
dagabu Posted July 22, 2010 Posted July 22, 2010 Im not a math guy, could someone take a look at the formula and post it please? Thanks for the catch Bonny!
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