Keeping spindle centered during pressing

[fr3dopyrox]

Hello,

i did some deep side scratches to my new spindle by pressing a 1 lb black powder rocket, which uses the little tube rolled in gummed tape? I wanted to know the length and diameter of this tube if possible thank you in advance ...

Edited October 24, 2020 by fr3dopyrox

[royster]

For 1lb i believe its 0.75 inches inside wall diameter and 7.5 inches length.

[justvisiting]

fr3dopyrox, that's my little trick. All tooling (even from the same toolmaker) has variations, so exact dimensions can't be given. Some drifts have 'steps' in the hole, which makes insertion difficult. Personally, I like to use rubber, if I can find the right size. In my most recently purchased set of 1lb BP tooling from Woody's, the bottom of my insert starts at just over 4 inches from the bottom of the first drift. The idea of the insert is for the tip of the spindle to enter the insert before the first increment starts being compressed. As the drift comes down, the drift is perfectly centered in the tube. When done correctly, the spindle will be quite snug in the insert after the first increment is pressed.

 

Another way to solve prevent this problem (which I feel is a design flaw), is to use a tube support that attaches to the spindle base. There would never be a misaligned spindle. To me, it's a safety issue that should not be over-looked. I know of two toolmakers that use this method for their own tooling. Commercial items are made in such a way that this potentially dangerous misalignment condition cannot occur. I think the root of the problem is that the best gold standard tooling is beyond the price that many are willing to pay, so toolmakers need to compromise somewhere. Extra bells and whistles are available for those willing to pay extra. I use the insert

[fr3dopyrox]

fr3dopyrox, that's my little trick. All tooling (even from the same toolmaker) has variations, so exact dimensions can't be given. Some drifts have 'steps' in the hole, which makes insertion difficult. Personally, I like to use rubber, if I can find the right size. In my most recently purchased set of 1lb BP tooling from Woody's, the bottom of my insert starts at just over 4 inches from the bottom of the first drift. The idea of the insert is for the tip of the spindle to enter the insert before the first increment starts being compressed. As the drift comes down, the drift is perfectly centered in the tube. When done correctly, the spindle will be quite snug in the insert after the first increment is pressed.

 

Another way to solve prevent this problem (which I feel is a design flaw), is to use a tube support that attaches to the spindle base. There would never be a misaligned spindle. To me, it's a safety issue that should not be over-looked. I know of two toolmakers that use this method for their own tooling. Commercial items are made in such a way that this potentially dangerous misalignment condition cannot occur. I think the root of the problem is that the best gold standard tooling is beyond the price that many are willing to pay, so toolmakers need to compromise somewhere. Extra bells and whistles are available for those willing to pay extra. I use the insert

Hello thanks for your clear reply !!! Where we can buy this rocket tooling ?

[justvisiting]

Maybe I misunderstood your problem. I thought you already have tooling? Are you wanting to use the little tube to prevent a problem from happening again, or are you saying the tube caused an issue? Black powder rocket tooling is commonly available from the usual suppliers, both here and in Europe. I get mine from Woodysrocks.com.

 

Even with a tube support, the spindle can easily become misaligned. This is because the downward pressing force can compress the tube lengthwise, which re-expands and pushes out the bottom of the tube support. We call this 'walking' in the support. If the support had a lip for the tube to sit on, that condition would not happen. If the support was attached to the spindle base, that wouldn't happen. It's a really easy fix, for a really common problem. Some toolmakers are receptive to suggestions for improvements. Some are not. Some toolmakers will add an extra feature for extra cost. Others would be offended at the suggestion that their tooling could be improved upon.

 

The insert idea is simply a workaround, and not the ideal way to solve the problem.

 

For people that hand ram rockets without tube supports, a fixture can be fabricated to keep the spindle in perfect alignment with the centre of the tube, which is detailed in Dave Sleeter's book on making amateur rocket motors.

 

One thing that can prevent misalignment is to level the increments before pressing/ramming. I use a piece of PVC pipe with little nicks in the end. I just drop it into the tube and give it a quick spin between finger and thumb to level the lower increments, and get the spindle started straight. It's a little bit of extra work, and it might not even really be necessary. I just feel that it's a good habit, so I do it. Some of my spindles are very long, so these habits can become more important.

[fr3dopyrox]

Maybe I misunderstood your problem. I thought you already have tooling? Are you wanting to use the little tube to prevent a problem from happening again, or are you saying the tube caused an issue? Black powder rocket tooling is commonly available from the usual suppliers, both here and in Europe. I get mine from Woodysrocks.com.

 

Even with a tube support, the spindle can easily become misaligned. This is because the downward pressing force can compress the tube lengthwise, which re-expands and pushes out the bottom of the tube support. We call this 'walking' in the support. If the support had a lip for the tube to sit on, that condition would not happen. If the support was attached to the spindle base, that wouldn't happen. It's a really easy fix, for a really common problem. Some toolmakers are receptive to suggestions for improvements. Some are not. Some toolmakers will add an extra feature for extra cost. Others would be offended at the suggestion that their tooling could be improved upon.

 

The insert idea is simply a workaround, and not the ideal way to solve the problem.

 

For people that hand ram rockets without tube supports, a fixture can be fabricated to keep the spindle in perfect alignment with the centre of the tube, which is detailed in Dave Sleeter's book on making amateur rocket motors.

 

One thing that can prevent misalignment is to level the increments before pressing/ramming. I use a piece of PVC pipe with little nicks in the end. I just drop it into the tube and give it a quick spin between finger and thumb to level the lower increments, and get the spindle started straight. It's a little bit of extra work, and it might not even really be necessary. I just feel that it's a good habit, so I do it. Some of my spindles are very long, so these habits can become more important.

Hello , thanks for this explanation, no I have my tooling from fire smith : I have 1lb bp rocket tooling and the tube support, I want make a little tube insert with gum tape, I think it is my cheap press who can to be the problem. I hope you understand my English : Im from Europe ,thanks... Edited October 25, 2020 by fr3dopyrox

[pyrojig]

One thing I found after extensive Reading, if spindle drifts to one side, add your increment of powder but hold the base and tube at a angle. Angle it towards to drift direction, the powder will be more on that side when you hand press the drift in. Ram it and gradually the drift will re center . Just my 2 cents

[justvisiting]

pyrojig, I have read that too. I don't like that idea very much. Make the spindle not be 'at an angle' in the first place- way better. IF the spindle is made of soft brass, 'straightening' the spindle actually bends it, if pressing at high force. I only use stainless steel spindles now.

 

IIRC, what pyrojig read was in one of David Sleeter's books. In that case, the rockets were being hand-rammed. Under those conditions, the advice would be good.

[NeighborJ]

The use of a spindle riser gives the clamp something to grasp for allignment. Sometimes this also requires the use of a longer tube support.

Some people drill and tap holes thru the spindle base into the support to securely fasten the base squarely to the support. This method works well if you aren't willing to invest in new tooling but requres a few extra steps during construction. A problem with this method sometimes occurs due to uneven wall thickness of the tubes themselves, if the tube ID is not concentric to the OD (as they commonly are) then both above mentioned centering methods are subject to cause the very misallignment they intended to cure.

 

The centering drift and fuel leveler method is the easiest method and these steps should be incorporated into all rocket builds even if you have a modified support capable of self centering.

[pyrojig]

Good point on the hand raming , that's exactly what I was referring to . I guess under high pressure of a press the dynamics change. I see it may pose a risk of bending . I too use stainless spindles. But do have a brass one that I had to un bend from a newbie using it. Edited November 11, 2020 by pyrojig