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Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work. |
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#1
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Busted power feed
On my bench-top mill , well it ain't busted no more ! Today I
replaced the speed control pot and reassembled it , installed it and it's working fine now . Since I was on a roll , i decided to set up the rotary table and engrave the dial for the X axis that I lost (original wouldn't work with the PF) when I installed the power feed . This machine uses 8 pitch leadscrews ... which means 125 divisions , which requires a 25 (or multiple) hole index plate with my 90:1 worm ratio . And I don't have one but I do have the time and material to make one ! Actually I'm making a 50 hole plate , got it machined to size and mounted in the rotary table and almost ready to drill . I figger it's best to bolt the RT down before I start ... -- Snag Illegitimi non carborundum |
#2
Posted to rec.crafts.metalworking
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Busted power feed
"Snag" wrote in message ...
On my bench-top mill , well it ain't busted no more ! Today I replaced the speed control pot and reassembled it , installed it and it's working fine now . Since I was on a roll , i decided to set up the rotary table and engrave the dial for the X axis that I lost (original wouldn't work with the PF) when I installed the power feed . This machine uses 8 pitch leadscrews ... which means 125 divisions , which requires a 25 (or multiple) hole index plate with my 90:1 worm ratio . And I don't have one but I do have the time and material to make one ! Actually I'm making a 50 hole plate , got it machined to size and mounted in the rotary table and almost ready to drill . I figger it's best to bolt the RT down before I start ... -- Snag ============================================ How? I've read of several possible ways to generate and test an index plate or similar geometric pattern but I've only tried two, and found them difficult without a DRO. The messiest was graduating a crossfeed dial for an AA/Sears lathe with a 5/16-24TPI LH thread. That's 41.67 lines per turn. |
#3
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Busted power feed
On 12/9/2020 6:06 AM, Jim Wilkins wrote:
"Snag"Â* wrote in message ... Â* On my bench-top mill , well it ain't busted no more ! Today I replaced the speed control pot and reassembled it , installed it and it's working fine now . Since I was on a roll , i decided to set up the rotary table and engrave the dial for the X axis that I lost (original wouldn't work with the PF) when I installed the power feed . This machine uses 8 pitch leadscrews ... which means 125 divisions , which requires a 25 (or multiple) hole index plate with my 90:1 worm ratio . And I don't have one but I do have the time and material to make one ! Actually I'm making a 50 hole plate , got it machined to size and mounted in the rotary table and almost ready to drill . I figger it's best to bolt the RT down before I start ... ------------------------------- How? I've read of several possible ways to generate and test an index plate or similar geometric pattern but I've only tried two, and found them difficult without a DRO. The messiest was graduating a crossfeed dial for an AA/Sears lathe with a 5/16-24TPI LH thread. That's 41.67 lines per turn. -------------------------------- That dial must have been a trip , how on earth did you resolve the partial space ? I used the rotary table to drill the 50 hole plate I needed to scribe 125 lines on the dial ... On my 90:1 RT , I moved 1 5/9 rotations per hole - 1 full turn and 20 holes on a 36 hole plate IIRC . The dial was 36 holes on the 50 hole plate ... and what's cool is that now I know how to do this , I can reproduce any hole pattern I need . -- Snag Illegitimi non carborundum |
#4
Posted to rec.crafts.metalworking
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Busted power feed
"Snag" wrote in message ...
On 12/9/2020 6:06 AM, Jim Wilkins wrote: "Snag" wrote in message ... On my bench-top mill , well it ain't busted no more ! Today I replaced the speed control pot and reassembled it , installed it and it's working fine now . Since I was on a roll , i decided to set up the rotary table and engrave the dial for the X axis that I lost (original wouldn't work with the PF) when I installed the power feed . This machine uses 8 pitch leadscrews ... which means 125 divisions , which requires a 25 (or multiple) hole index plate with my 90:1 worm ratio . And I don't have one but I do have the time and material to make one ! Actually I'm making a 50 hole plate , got it machined to size and mounted in the rotary table and almost ready to drill . I figger it's best to bolt the RT down before I start ... ------------------------------- How? I've read of several possible ways to generate and test an index plate or similar geometric pattern but I've only tried two, and found them difficult without a DRO. The messiest was graduating a crossfeed dial for an AA/Sears lathe with a 5/16-24TPI LH thread. That's 41.67 lines per turn. -------------------------------- That dial must have been a trip , how on earth did you resolve the partial space ? I used the rotary table to drill the 50 hole plate I needed to scribe 125 lines on the dial ... On my 90:1 RT , I moved 1 5/9 rotations per hole - 1 full turn and 20 holes on a 36 hole plate IIRC . The dial was 36 holes on the 50 hole plate ... and what's cool is that now I know how to do this , I can reproduce any hole pattern I need . -- Snag ======================= I put the locking screw between lines 0 and 40. It didn't take long to realize that the AA/Sears lathe wasn't practical to turn steel so I went looking for a better lathe and found the 10" South Bend. The AA was demoted to grinding and polishing, and drilling small deep holes. However last night I used the SB to drill a 1mm hole in the end of a 4-40 screw for the music wire drive pin in a gauge pointer puller: https://www.pressuregauge.co.uk/acce...removal-tools/ I made the tool quickly and roughly from water pipe to fix the gauge, then decided it was an interesting shape worth cleaning up and polishing. The formula is simple, 90/125 handle revs per division, but the fractional math can be difficult to match to available hole circles. I reduce the numbers to prime factors, in this case 90=2*3*3*5 and 125=5*5*5, instead of trying to convert calculated decimals to fractions. Removing all factors common to both leaves 2*3*3 / 5*5, or 18/25 or multiples thereof. My second hand RT is 40 turn and I made a spreadsheet that gives the turn + hole settings. The RT had only one plate so I've had to find ways to index what it couldn't. I indexed 13 spline grooves to fit a motorcycle sprocket to my sawmill's transmission with the 54 tooth change gear from the AA lathe. Fortunately the RT's plate had the 17 hole circle to mill a 68 tooth steering sector gear for my tractor. 40/68 = 2*2*2*5 / 2*2*17 |
#5
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Busted power feed
"Jim Wilkins" wrote in message ...
"Snag" wrote in message ... You can easily write a spreadsheet that gives the indexing settings. I used free OpenOffice. Type in what's between the quotes below. I type the file name in cell A1. Enter "Divisions" in A2, "1" in A3, and the formula "=A3+1" in A4. Copy and paste A4 down column A as far as you want. You can always extend it. Enter "90" in B2 and the formula "=$B$2/A3" in B3. Change the format of B3 to Fraction and change the code to '# ???/???". "# ??/??" is OK up to 100., and neater. Copy and paste B3 down as far as you did A3. Column A lists the number of divisions, B gives the full and fractional turns for it. |
#6
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Busted power feed
On 12/11/2020 9:43 AM, Jim Wilkins wrote:
"Jim Wilkins"Â* wrote in message ... "Snag"Â* wrote in message ... You can easily write a spreadsheet that gives the indexing settings. I used free OpenOffice. Type in what's between the quotes below. I type the file name in cell A1. Enter "Divisions" in A2, "1" in A3, and the formula "=A3+1" in A4. Copy and paste A4 down column A as far as you want. You can always extend it. Enter "90" in B2 and the formula "=$B$2/A3" in B3. Change the format of B3 to Fraction and change the code to '# ???/???". "# ??/??" is OK up to 100., and neater. Copy and paste B3 down as far as you did A3. Column A lists the number of divisions, B gives the full and fractional turns for it. If I run into roblems calculating the turns I just refer to Ivan Law's gear cutting book from the workshop series - #17 IIRC . I do this so seldom that I'd lose the spreadsheet ... -- Snag Illegitimi non carborundum |
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