Re: Clamping large dia. for centre-drilling
Reduced shank drill or 3/8 chuck fitted to Unimat.
-----Original Message-----
The drill is too big for the 0-? in Jacobs chuck.
?
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Re: Clamping large dia. for centre-drilling
The drill is too big for the 0-? in Jacobs chuck. ? I guess they want the drill held in the 3 jaw chuck in the headstock but then the workholding arrangement is a bit of a mystery. As you have noticed you need to hold it so that the centre mark is at the lathe centre height. You also need to ensure it is horizontal and aligned with the bed bars too otherwise the hole will be on a skew. ? Or maybe use the drilling column (if you have one) and hold the work upright? ? I guess it all depends on what bits and pieces you have to hold the work… which is a question that will keep on coming up. ? Regards, Andy ?
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From: [email protected] [mailto:[email protected]] On Behalf Of Martin P. via groups.io
Sent: 23 April 2020 19:12
To: [email protected]
Subject: Re: [Unimat] Clamping large dia. for centre-drilling ? Instructions seem odd. The standard way of doing such a bore is TS drilling - but the workpiece is too long for that. How I would do it is use the extended way bars, intended for wood turning. Clamp the workpiece in the 3-jaw, support it near the end with the steady rest. and put the TS on the extended end of the way bars for drilling. Now, I realize this does not help you if you have neither the extended way bars or the steady rest. But those are two invaluable accessories for TS drilling on the Unimat (DB/SL). -----Original Message-----
From: William Ayerst <willayerst@...>
To: [email protected]
Sent: Thu, Apr 23, 2020 1:35 pm
Subject: [Unimat] Clamping large dia. for centre-drilling Hello again chaps,
Last question for a long time I hope - I’ve got the majority of techniques tested for the Edenstaal cannon - the last question on it, I hope is that it suggests to centre punch the ends (of a 6” x 1” dia aluminium rod) for a cannon barrel - but then says ‘clamp the work to the tool post, using a 3/8” drill in the headstock bore the barrel to a depth of 2 3/4”.
On the face of it, this doesn’t seem like an unreasonable ask - but after checking it looks like there’s a problem:
- I have the machinist vice attachment, and it just about has capacity for the 1” dia rod on the flats of the jaws (which I’ve heard is bad practise) -but the resultant centre line position of the clamped rod is way higher than the headstock centre.
- I also have a milling table attachment I can put on the toolpost, but that raises it up even higher!
The only thing that comes to mind, is using the strap clamps from the milling table directly in the t-nut slot on the tool slot!
Hopefully, that’s my last query - thank you all so much for the help, hopefully some output will be here shortly!
Cheers,
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Re: Clamping large dia. for centre-drilling
Instructions seem odd. The standard way of doing such a bore is TS drilling - but the workpiece is too long for that.
How I would do it is use the extended way bars, intended for wood turning. Clamp the workpiece in the 3-jaw, support it near the end with the steady rest. and put the TS on the extended end of the way bars for drilling.
Now, I realize this does not help you if you have neither the extended way bars or the steady rest. But those are two invaluable accessories for TS drilling on the Unimat (DB/SL).
Martin
-----Original Message-----
From: William Ayerst <willayerst@...>
To: [email protected]
Sent: Thu, Apr 23, 2020 1:35 pm
Subject: [Unimat] Clamping large dia. for centre-drilling
Hello again chaps,
Last question for a long time I hope - I’ve got the majority of techniques tested for the Edenstaal cannon - the last question on it, I hope is that it suggests to centre punch the ends (of a 6” x 1” dia aluminium rod) for a cannon barrel - but then says ‘clamp the work to the tool post, using a 3/8” drill in the headstock bore the barrel to a depth of 2 3/4”.
On the face of it, this doesn’t seem like an unreasonable ask - but after checking it looks like there’s a problem:
- I have the machinist vice attachment, and it just about has capacity for the 1” dia rod on the flats of the jaws (which I’ve heard is bad practise) -but the resultant centre line position of the clamped rod is way higher than the headstock centre.
- I also have a milling table attachment I can put on the toolpost, but that raises it up even higher!
The only thing that comes to mind, is using the strap clamps from the milling table directly in the t-nut slot on the tool slot!
Hopefully, that’s my last query - thank you all so much for the help, hopefully some output will be here shortly!
Cheers,
|
Clamping large dia. for centre-drilling
Hello again chaps,
Last question for a long time I hope - I’ve got the majority of techniques tested for the Edenstaal cannon - the last question on it, I hope is that it suggests to centre punch the ends (of a 6” x 1” dia aluminium rod) for a cannon barrel - but then says ‘clamp the work to the tool post, using a 3/8” drill in the headstock bore the barrel to a depth of 2 3/4”.
On the face of it, this doesn’t seem like an unreasonable ask - but after checking it looks like there’s a problem:
- I have the machinist vice attachment, and it just about has capacity for the 1” dia rod on the flats of the jaws (which I’ve heard is bad practise) -but the resultant centre line position of the clamped rod is way higher than the headstock centre.
- I also have a milling table attachment I can put on the toolpost, but that raises it up even higher!
The only thing that comes to mind, is using the strap clamps from the milling table directly in the t-nut slot on the tool slot!
Hopefully, that’s my last query - thank you all so much for the help, hopefully some output will be here shortly!
Cheers,
|
Re: Offset headstock measurement ?
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Re: Cap for coal/spring assembly
My local hardware store has solid plastic rod in various diameters. If you can cut an internal 1mm thread, machining these should be possible.
On Wed, Apr 22, 2020 at 10:36 AM Berniesbits via <berniesbits= [email protected]> wrote: If I remember correctly the cap thread is 9mm x 1mm pitch. ? ?
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Re: Offset headstock measurement ?
No misprint. The Unimat DB/SL HS offsets, the TS doesn't. The following is the correct procedure, per "bluerandonee":
Put a dead center in the spindle. Clamp a machinists scale on top of a bit in the tool holder on the cross slide (make sure it is set to 90 degrees). Adjust the cross slide until an inch line meets the dead center point. Remove the locating pin and loosen the tightening bolt and rotate the headstock counterclockwise until you measure 9/64". Because
the tip of the dead center will move in an arc you may need to move the
cross slide slightly toward the headstock for an accurate measurement. Lock the headstock in place.
-----Original Message-----
I think that there is probably a misprint in the directions. To turn a taper between centers I would offset the tail stock from the center line between the head stock and tail stock. I don’t have my uni out to look at it right now but I don’t remember unit having the centering scale at the end of the tail stock to measure how far off they are. My two large lathes have this scale. Have to confess though that I haven’t turned tapers between centers in about twenty years as I cheat and use taper attachment on one of the large lathes when needed.
Good luck, SSK
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Re: Offset headstock measurement ?
On my U3 I would instead use the topslide....(Compund0 to turn the taper into the barrel blank.? Turning between centers using the faceplate and dog, Never tried it seems possible
Ed
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Re: Cap for coal/spring assembly
Hello Magnus, Just curious to know if you have had time to look at the bakelite caps on your scrap motor? Min mejladress: hakanssondahlberg@....? -- Lars H
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Re: Offset headstock measurement ?
I think that there is probably a misprint in the directions. To turn a taper between centers I would offset the tail stock from the center line between the head stock and tail stock. I don’t have my uni out to look at it right now but I don’t remember unit having the centering scale at the end of the tail stock to measure how far off they are. My two large lathes have this scale. Have to confess though that I haven’t turned tapers between centers in about twenty years as I cheat and use taper attachment on one of the large lathes when needed.
Good luck, SSK
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Re: Offset headstock measurement ?
Put a dead center in the spindle.
Clamp a machinists scale on top of a bit in the tool holder on the cross slide (make sure it is set to 90 degrees).
Adjust the cross slide until an inch line meets the dead center point.
Remove the locating pin and loosen the tightening bolt and rotate the headstock counterclockwise until you measure 9/64".
Because the tip of the dead center will move in an arc you may need to move the cross slide slightly toward the headstock for an accurate measurement.
Lock the headstock in place.
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Re: Offset headstock measurement ?
If I am holding the barrel blank in my 3 or 4 jaw, I have excess material at the breech.? I wouldlet my tool touch the blank at the muzzle end and back the cross slice out 3.57 mm 3.55 or 3.6 easy marks on the handwheel.? Swing the headstock so the tool touches the muzzle end of the cannon blank and lock the headstock you should have your taper dialed in
Ed Samsen
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Re: Offset headstock measurement ?
The point of a dead center inserted into the tailstock and the tailstock moved as far left as possible would (should, ought) give you the datum for measuring headstock offset from.
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On Apr 22, 2020, at 08:29, William Ayerst <willayerst@...> wrote:
?Thanks Alf - I'm a little confused as to what my datum point would be - presumably I could set a tool at the edge of the faced rod at one extreme end of the taper, and then rotate the headstock so the distance between the tool and the work is now 9/64" (i.e. 140 thou) - just wasn't sure that's what I needed!
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Re: Offset headstock measurement ?
Thanks Alf - I'm a little confused as to what my datum point would be - presumably I could set a tool at the edge of the faced rod at one extreme end of the taper, and then rotate the headstock so the distance between the tool and the work is now 9/64" (i.e. 140 thou) - just wasn't sure that's what I needed!
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Re: Offset headstock measurement ?
I can't specifically address your numbers there, but I can see my way to working out the geometry first on paper. Personally I either remember back to high school geometry and when that fails me - it _has_ been 62 years - I go to google for geometric problem solving.
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On Apr 22, 2020, at 07:52, William Ayerst <willayerst@...> wrote:
?Reading the project files ‘Edenstaal Cannon’ - page 1 talks about offsetting the headstock to attain a taper. I’ve tried this with some brass and so I’m broadly familiar with the idea, but actually measuring it is a mystery to me. The text reads:
‘Place the faceplate on the lathe and mount the work between centres, driving with a lathe dog. Offset the headstock away from the tool post by 9/64” and turn the tapered portion of the barrel as illustrated’
How do I measure this 9/64” offset? From where??
Many thanks,
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Offset headstock measurement ?
Reading the project files ‘Edenstaal Cannon’ - page 1 talks about offsetting the headstock to attain a taper. I’ve tried this with some brass and so I’m broadly familiar with the idea, but actually measuring it is a mystery to me. The text reads:‘Place the faceplate on the lathe and mount the work between centres, driving with a lathe dog. Offset the headstock away from the tool post by 9/64” and turn the tapered portion of the barrel as illustrated’How do I measure this 9/64” offset? From where??Many thanks,
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Re: Cap for coal/spring assembly
What a good idea, I never though of making a thread this way.
Thanks for the tip.
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Re: Cap for coal/spring assembly
you could also wrap some plastic wrap around the threads & form some epoxy putty around it to make a cap,
On Monday, April 20, 2020, 11:08:54 PM PDT, <hakanssondahlberg@...> wrote:
I found the file and have sent him a mail. Thank you for the tip!
--
Lars H
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Re: Cap for coal/spring assembly
I found the file and have sent him a mail. Thank you for the tip!
--
Lars H
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Bubba Kay
Les Orton