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Thread: What to do, what to do...
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11th August 2013, 09:53 PM #16GOLD MEMBER
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What is the overall length of your original nut?
What is the length of the cylindrical nut you have?
What is the length of the spigot on the nut?
What is the diameter of the spigot?
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11th August 2013 09:53 PM # ADSGoogle Adsense Advertisement
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11th August 2013, 10:02 PM #17Philomath in training
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What is the overall length of your original nut? 32.13mm
What is the length of the cylindrical nut you have? 25.60mm
What is the length of the spigot on the nut? 10.37mm
What is the diameter of the spigot? 12.70mm
Michael
to answer the next post, I wasn't able to get an acme tap so bought a COTS nut to adapt. I did hope that the OD would be large enough that I could machine it to size, but this is a different brand than the last ACME nut I bought. The thread is 1/2" 8tpi. While I have single point cut internal ACME threads, I find those smaller sizes awkward to do and I have my doubts about the accuracy of the form I am producing - hence the purchased nut.Last edited by Michael G; 11th August 2013 at 10:14 PM. Reason: Added a bit
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11th August 2013, 10:05 PM #18GOLD MEMBER
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Were you able to source a suitable tap at any stage,or would you consider turning the thread.
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11th August 2013, 10:15 PM #19Pink 10EE owner
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I would bush the old nut myself... The shear strength of the higher strength loctite products is very impressive, you do not need a press fit just a smooth transition fit..
it is not the only nut in the country if u need a reference...
I will have a stab and guess my 10EE top slide is the same... If so for a look at non-genuine replacement part prices Compound Screw for Monarch 10EE
items in monarch store on eBay!
Cross Slide Screw for Monarch 10EELight red, the colour of choice for the discerning man.
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11th August 2013, 10:34 PM #20GOLD MEMBER
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Have you considered changing the thread to a more common size.
You could then either machine a new screw or replace the threaded section only.
You could either cut an internal thread or buy a tap to suit,into a hercus cross slide nut blank casting.
Easiest to source would probably be 1/2 x 10 TPI.
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11th August 2013, 10:39 PM #21Philomath in training
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Yes, your cast nut looks just as ratty as mine does. Good to know there is another one out there.
The various loctite suggestions are getting more and more attractive. While the silver solder option is simple and should work, I do worry about the possibility of it moving or distorting and throwing the alignment out. If I made up a jig that located on the spigot and sides of the nut, boring an accurate hole should not be a difficult issue even if positioning it in the right location is.
Michael
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12th August 2013, 10:13 PM #22GOLD MEMBER
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Hi Michael,
I like the idea of making a "Jacket" to suite the existing mounting with a dowel pin out of steel. Then bore out this jacket and/or turn down the new nut to a snug fit and loctite it in. I have been impressed with loctite too as I have recently used it on the rebuilding of this bandsaw.
WRT turning down the nut and how to hold it in place and have it turn out concentric, how about threading it onto the compound leadscrew, loctiting it in place (don't use a super strong one) half way, and using the leadscrew between centres to turn down the nut. Could also be easily removed to check for fit, although with these loctite products, the type of fit does not seem to be critical.
If you stuff it up (not that you would ) then at worst you're up for a new piece of scrap steel, bit more time and maybe a new nut. BUT, your old nut gets to stay original..... You could even mount it behind glass.
Just a thought,
SimonGirl, I don't wanna know about your mild-mannered alter ego or anything like that." I mean, you tell me you're, uh, super-mega-ultra-lightning babe? That's all right with me. I'm good. I'm good.
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21st September 2013, 09:53 PM #23Philomath in training
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So what did he do?
The eventual solution was a bit of everything - turning the nut down, using bearing locker, putting a pin in to lock the nut.
Rather than attack the original nut which was cast and did not have much meat on it, I made up a nut from solid PhBr. The centre hole was reamed out to 16.05, and the nut OD turned to 16.02. A generous slosh of bearing locker and the result was
P1010881 (Medium).JPG
The thread is recessed was because the bought nut was 24.6 long and the outer was 28 (size of the contributing offcut). I did think about shortening it but it is already shorter than the original, so decided not to bother. To bore the hole for the middle I used the Taster to position the outer on the mill. It took some time to get the probe concentric with the machine spindle adaptor but after doing that it certainly made getting things positioned easy.
Here's the nut in it's mounted position. I installed a roll pin to lock the inner to the outer. It just interferes with the outer diameter of the inner nut without breaking through to the thread.
P1010884 (Medium).JPG
The good news is that I think I'm very close to the zero backlash that I was chasing. Using a 0.01mm DTI I'm getting less than 5/10th change on the compound dial when the needle moves 1/2 to 1 division (0.01mm = 4/10th thou, so about what would be expected if close to zero backlash). I should probably do this test with a 1/10th indicator
The bad news is that more work is required. I scraped the bottom of the compound and matching slide surface back to cheeseboard (this was another slide that had been used without lubrication, so oil grooves have now been added too) but from the way the slide gets tighter towards the far end, so I'm guessing that the dovetails have enough wear in them that they will need to be done too. I may also need to shim the nut assembly up maybe 0.05mm to 0.1mm as I'm also getting some binding at the near end, but I'll see how the dovetails go first.
Michael
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21st September 2013, 10:06 PM #24
Glad to see its sorted Michael
Am i right in thinking that the CVA is like the Rivett, the slide contacts not only on the bottom flats but on the top ones too (either side of the nut)?
Ew1915 17"x50" LeBlond heavy duty Lathe, 24" Queen city shaper, 1970's G Vernier FV.3.TO Universal Mill, 1958 Blohm HFS 6 surface grinder, 1942 Rivett 715 Lathe, 14"x40" Antrac Lathe, Startrite H225 Bandsaw, 1949 Hercus Camelback Drill press, 1947 Holbrook C10 Lathe.
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21st September 2013, 10:50 PM #25Philomath in training
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No - contact is on the bottom flats and the undersides of the dovetails. The top flat is in clearance (but not by much). I ran over it with the scraper as it looked pretty ordinary. I figured that a scraped surface would look nicer than discoloured cast iron, complete with some pitting and cutter marks.
Michael
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21st September 2013, 10:53 PM #26
Isn't it funny, we see scraped surface and we think "precision" automatically.....well i do anyway
1915 17"x50" LeBlond heavy duty Lathe, 24" Queen city shaper, 1970's G Vernier FV.3.TO Universal Mill, 1958 Blohm HFS 6 surface grinder, 1942 Rivett 715 Lathe, 14"x40" Antrac Lathe, Startrite H225 Bandsaw, 1949 Hercus Camelback Drill press, 1947 Holbrook C10 Lathe.