- Thread starter Bki26
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if you could get it set up correctly think this would be the quickest way...lock the carriage and 'part off' with a ground hss tool like in this video (timestamped)
can't remember now
but I pretty much copied that video with some experimenting and ended up with this, the rounded shape on the head side threaded in the easiest
The part uses 3 of these shoulder bolts, the outer 2 are fine as is but the middle one is going into a 5mm thick section when the thread is 9.5mm long. Already tried and it's cheaper to buy the standard and cut the thread if I wanted them custom made it would be 2x the price.
Run in reverse was the plan.
Would damage the anodised aluminium and look terrible.
When I unscrew it'll reform the thread if it's slightly rounded, yes I could chamfer however any time I've tried to do that it always made the thread worse so I preemptively put a nut on most bolts before cutting
if I take my 30° insert holder and set it up perpendicular I could probably plunge to part and chamfer the thread in one go but otherwise I'm fine with flat hence parting and reforming via unscrewing since once the bolt is in its getting thread locker applied, I just need a length of thread that won't be sticking out the back catching on clothes.
That's what I was thinking, I made a little brass insert for the travelling steady threaded hole mount as it's exactly on the ways so tightening down the grub screw that sits im the hole when no steady is attached pinches against the ways and locks the carriage.if you could get it set up correctly think this would be the quickest way...lock the carriage and 'part off' with a ground hss tool like in this video (timestamped)
can't remember now
View attachment 504564
I'll watch the full 2 part video thanks
8ob
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Hello BKI26,
you need a steady to support the bolt so you can part off the excess, holding the head in the chuck.
It depends on what lathe size you have, as it is quite a small screw, but if standard fixed or moving steadies are not practical it is an option to make a support that fixes to the lathe carriage.
Another option are, what I think are called box tool holder as used on the old fashioned capstan lathes, which both support and cut simultaneously.
Alec
you need a steady to support the bolt so you can part off the excess, holding the head in the chuck.
It depends on what lathe size you have, as it is quite a small screw, but if standard fixed or moving steadies are not practical it is an option to make a support that fixes to the lathe carriage.
Another option are, what I think are called box tool holder as used on the old fashioned capstan lathes, which both support and cut simultaneously.
Alec
Morrisman
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A 45° chamfer will sort the sharp edge of the thread and save a fair bit of work. Make a combination part off and chamfer tool from HSS.When I unscrew it'll reform the thread if it's slightly rounded, yes I could chamfer however any time I've tried to do that it always made the thread worse so I preemptively put a nut on most bolts before cutting
I sold my own lathe just a few days ago, gave the tools and everything with it, or I could have showed you perfect examples of the collet and parting off tool.
Maker
Most folk just call me; Orange Joe
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Clearly your labour rate is too low!
If I had to machine those I think I'd hold them by the head (probably in a collet chuck) and use a centre in the tailstock as a stop. It might need a travelling steady but I think a standard one would be too thick.
GS Fasteners Ltd - Specialist Fasteners and Turned Components
GS Fasteners manufacture and supply non-standard fasteners and screwed components not normally available off the shelf.
gsfasteners.co.uk
For a 1/4 UNC x 3/4" captive screw in mild steel, we pay £6.50 each. GSF could supply in stainless for 64p.
I do have a small piece of hss bar stock from a friend somewhere, if I grind it as you say into a stubby parting tool with 45° edge then I can do both operations with just the Y axis like I intended.
Paid something like less than 20p for each anyway.
Just find a secure way of holding the screw (Mole grips or similar), and use a grinding wheel, to get to the required length, then hand hold the screw to put a slight chamfer on the end.
I can see this becoming a "how to get the table out of the van" thread ;-)
I can see this becoming a "how to get the table out of the van" thread ;-)
But by the time you've thought about it, created a holder, done it, de-burred them . . . you are working for less than nothing . . .
Erie Fred
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Very nicely done sir ^^^
If you had a a back toolpost, the cross slide could be set-up to do it all with no special
ground tooling.
On this set-up pix below, the cross slide is pulled from the back to apply the swing down stock stop, bar or part is set for length, collet closed.
Advance cross slide forward (or up in this pix) facing off bar, and then nicking in 2 chamfers (both ends of the soon to be parted off piece) end turret does some drilling, and then the cross slide is advanced backwards (down in this pix) to bring
the part off tool into play (the stock stop now has clearance to pass beyond center as the part was faced
in the previous operation)
If you had a a back toolpost, the cross slide could be set-up to do it all with no special
ground tooling.
On this set-up pix below, the cross slide is pulled from the back to apply the swing down stock stop, bar or part is set for length, collet closed.
Advance cross slide forward (or up in this pix) facing off bar, and then nicking in 2 chamfers (both ends of the soon to be parted off piece) end turret does some drilling, and then the cross slide is advanced backwards (down in this pix) to bring
in the previous operation)
Well the good news is the setup works however I now have to deal with trying to sharpen the hss parting blade so it actually cuts and doesn't burn out the stainless or make it jump on the blade!
Might just mount the dremel with cutoff discs in the toolpost.
Might just mount the dremel with cutoff discs in the toolpost.
I'm pleased you've settled on finding a method to cut a chamfer on the end of the thread. Even on a cottage industry product, I'd be pretty disappointed to find a shortened thread left square and sharp.
How are you holding your collet chuck in the spindle? If it's not on an integrated face plate, I'd be inclined to grip the body with shims around the knurl. Also what lathe are you using? If it's a little hobby lathe, you might struggle to achieve the rigidity to really make a good go of it and maintain any tool life.
If you're struggling with the parting, another possibility would be to rough them to approximate length with one of the previously discussed savage methods and then finish them with the form tool, but at that point, @bricol might have your answer. You don't necessarily have to go at the excess length with a parting cut though. Since you're only taking 4.5mm off, you could grind a tool with a longish 30° chamfer that takes the length down as an inclined full depth facing cut (feeding radially) and then transition into the chamfer.
How are you holding your collet chuck in the spindle? If it's not on an integrated face plate, I'd be inclined to grip the body with shims around the knurl. Also what lathe are you using? If it's a little hobby lathe, you might struggle to achieve the rigidity to really make a good go of it and maintain any tool life.
If you're struggling with the parting, another possibility would be to rough them to approximate length with one of the previously discussed savage methods and then finish them with the form tool, but at that point, @bricol might have your answer. You don't necessarily have to go at the excess length with a parting cut though. Since you're only taking 4.5mm off, you could grind a tool with a longish 30° chamfer that takes the length down as an inclined full depth facing cut (feeding radially) and then transition into the chamfer.
Spindle bore has an mt3 taper and collet chuck is mt2 for the mill so bought an adapter and made a spacer so I can use the mill drawbar in the lathe
Had an idea at midnight so created and printed this in 30m and works a treat! Just needs a packer and the ziptie to increase the rigidity slightly as the gyroscopic effect already helps keep it in position
Now I get the best of both worlds, accuracy with the lathe and easy cutting with the grinder lmao plus I don't need to prethread a nut before cutting to chase the thread after as it's such a clean cut there's no resistance when screwing in by hand.
