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I Forge Iron

Rob G

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Posts posted by Rob G

  1. i guess the force a flypress can deliver depends mostly on the lead of the screw and the weight of the wheel. i'm punching 2.5" holes through 3" thick aluminum. can that be done on a flypress in the size range oldworld anvils offers?

  2. ok i already posted the answer twice yet no one has picked up on it.

    the answer is the screw is going to be a 4 start w/ a 1" pitch. this answers all the information needed in order to cut the screw and meets the original requirements of having a 4" lead and setting the lathe at 1/4 tpi.

  3. your elementary explanations are frustrating as they reveal you don't understand what my problem here was. yes hw i'm aware of what starts are and machinery's handbook. the question is do you even understand what my problem is before you even give me advice.

  4. another dim light bulb moment, and i think i got it this time.

    with a pitch of 1, this gives 4" lead with 4 starts as the lead is number of starts times pitch. lathe is set at 1/4 tpi as required

    this is right, and i'm trying to write an explanation, but it is so hard for me to articulate. for example the first thing i say in my idea above is "with a pitch of 1". i give no citation as to how i came up with this figure and it appears i snagged it out of thin air. however, now that the numbers are written down, they can be run through and proved correct so it really doesn't matter. i suppose as long as you have an understanding it doesn't matter whether or not you can articulate.

    what makes it so odd to explain is that it was figured using the relationship between the required lead and the required setting the lathe at 1/4 tpi. this is NOT the order that most screws are figured in, but it had to be done this way with this screw because it is so different. while i did figure it out i'm sure there is a better way to understand this.........

  5. the screw in that link is 1" lead. i need 4" lead.

    John B, i'm sorry, i meant 1/4 tpi, not 1/4" pitch. i've since edited the post. that is 1/4 tpi per thread. the actual pitch after all multiple starts is not known because the number of starts has not yet been figured.

  6. it's got to be figured so that there is no extra lands in between each thread. for example if i were to do just 4 starts there would be large lands between each thread. there is some type of relationship for thread size, involving diametral pitch, pitch, lead, helix angle..... i don't know, tryin to figure it out.......

  7. OK, i've got to turn a screw here. This thing has to be 2-1/4" OD. 4" Lead. Now how do i figure how many starts this screw will have. I know the diametral pitch is 12.5663 and the helix angle is 9.869572 if my calculations are correct. i want it to be 1/4 tpi per thread for the reason that my lathe can cut down to 1 tpi, and i have change gears for it to get it down to 1/4. now where do i go from here. if i'm not mistaken, this thing will be figured out more like a helical gear than a screw.

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