Jump to content
APC Forum

Much BP & Labour spent


SKC

Recommended Posts

I've spent 50gm BP to lift 150gm shell. So spent 700gm for 14 shells to good height in total.

The BP was not from mill powder & bonded without dextrin. Green mix was 200mesh & completely dried to crispyness.

The first shell was only lifted upto around 60feet & bursted after falling on ground.

Then I inserted a hard cardboard disk atop and jammed top of the shell-head into morter to 6inch with pressed newspaper. Then enough pressure was created and I got good height. And side clearing of shell & mortertube was not more than 2mm.

But I have seen people getting orbital height with only BP & less in amount.

Please help me advising what went wrong on this context. Is something to be added to boost BP power or any trick involved?

It'll be of immense help & thanks in advance.

Link to comment
Share on other sites

What charcoal was used and what was the mesh size of your bp? How was it granulated? Screen mixed BP can be used for lift, but its quality is highly dependant upon type and fineness of the charcoal.
Link to comment
Share on other sites

  • 2 weeks later...

You would do well to invest in a ball mill. You might be able to make acceptable lift with greenmix, but you're going to spend way to much time doing so. On the other hand you can buy a small mill off ebay for only US$50 with shipping and make consistently good BP with little effort.

Link to comment
Share on other sites

The shell should fit snugly in the mortar tube. 2mm space is already too large. You can wrap some soft paper around the shell as a padding, but in a way that it unwraps before the shell bursts.

  • Like 1
Link to comment
Share on other sites

The shell should fit snugly in the mortar tube. 2mm space is already too large. You can wrap some soft paper around the shell as a padding, but in a way that it unwraps before the shell bursts.

 

2mm clearance is pretty tight. A snug fit will use the lift more efficiently, but good lift will work well even with a slightly looser fit. Typically the goal is to have a shell at 90-95% of the mortar diameter.

 

If your only option for lift is green mix or generally weak powder you might consider lifting Maltese style using a bp maroon and lift disk. That's similar to what you did with your newspaper wad.

Link to comment
Share on other sites

  • 3 weeks later...

I had the same issue just starting. I now make and ERC for charcoal and got a ball mill. I was not using the right charcoal and my lift was pathetic. I gave up and started over. I now burn my own ERC and it is amazing. I first used the coffee grinder method until I could easily screen it through 100+ screens. Still did not work as well as milling. Running the components in the mill prior to mixing and then as a hot mix. It is not a cheap hobby to get started with, but if you get good tools they will last you a long time and make things easier.

Link to comment
Share on other sites

If you want to make good BP, a ball mill is not optional. Unless, of course you don't mind grinding away by hand with a mortar and pestle for four or more hours. A ball mill doesn't have to be a big outlay of money either; I built my own for around $20. It isn't the biggest and can only handle 125 grams maximum, but it consistently makes batches of great BP.

Edited by MadMat
Link to comment
Share on other sites

×
×
  • Create New...