Re: Direct Reading cross feed dial.
"" by Martin Cleeve discusses the compound set over method vs advancing both cross and compound slides.? This book is well worth its modest cost.? Cleeve made his living doing short production runs threading parts for companies.
Cleeve suggests that set over should be 29 degrees rather than 29.5 to ensure that the right flank is shaved with each pass so it does not develop a stairstep roughness due to minor effects.
Cleeve favored keeping the compound at 90 degrees, so he advanced both cross and compound slides.? Rather than using trigonometry he simply advanced the compound half of the amount that he advanced the cross slide - this ensures the right flank is shaved on each pass, similar to a set over of 29 degrees.? This allows using a tool ground for the finest thread, then when depth is reached the compound is advanced to achieve the correct thread root width.? With the set over method the tool point width should be reground to the correct width for each different TPI to achieve the correct root width.
Also, since Cleeve made his living threading, he designed and built a dog clutch for his Myford lathe.
John
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Re: New topic ¡ª- Cutting a thread for a very old wooden clamp.
?Dear All,
My original one, (complete) is probably 150 years old, possibly more.
The broken one is probably the same vintage, albeit smaller. This is the one I would like to restore at some point. I have got quite a few clamps for woodworking but the working one has the longest reach.
The original thread(s) measures ~ 5/8¡± x ~ 6. Look at the detailed image.(You can see even the 6 TPI is not perfect.) JFI - Hence my scribble says ¡°Seems to be ~ 5/8 x 6 TPI. (I¡¯m sure you all understand but just in case the symbol for approximately is ~.)
I don¡¯t think anyone makes a 5/8 x 6 wood tap/die any more. Hence my request for assistance and using my 7 x 12 mini lathe. (Dare I mention the words after the recent discussion ?. ?) I was wondering if I could increase the thread to the more usual 3/4¡± x 6?
I think(?) the thread is made of beech.
I hope this is useful.
Thank you to all those who have offered help and assistance.?
PS As we all say, ¡°You never stop learning - Every day is a day at school!
Regards,
David (UK)
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On 28 Jan 2024, at 20:03, mike allen <animal@...> wrote:
?like these ?
thanks
animal
On 1/28/24 12:01 PM, David Wiseman wrote:
They are of the style of an engineers hand clamp but really HUGE in comparison and of course made of wood.
Best regards
David
On 28 Jan 2024, at 19:01, mike allen <animal@...> wrote:
?Are these clamps the " hand screw " clamps ? They have left & right hand
threads . I've never seen a set with wooden screws .
animal
On 1/15/24 11:39 PM, DAVID WILLIAMS via groups.io wrote:
Dear All,
I realise this is both part Mini lathe and part wood lathe. But to me the metal lathe part is more important. Hence my question to you all.
I have a couple of these old wooden clamps - probably antique. They are just like the metalwork ones we use, but much much larger. One has a severely damaged (external) threads.
I would like to try(?) and cut the replacement long wooden thread on my 7 x 12. So, I bought a second hand thread chaser on eBay. It¡¯s 6 TPI and according to the chart on the Little Machine Shop site - the gear set up is no problem on my imperial lathe.
[JFI it¡¯s Real Bull model purchased from Chester Machines (in the UK) some 20+ years ago. If that¡¯s at all relevant?]
The thread chaser cuts multiple threads at the same time and the tool (normally hand held I understand) needs to be held at ~ 90 degrees to the thread, unlike the usual angle for cutting one side of a metal thread. OR, if you are doing it by hand, do you angle the thread chaser so it cuts a series of slightly deeper threads. Thus the tool needs to be held in the tool post at a similar angle?
Assuming I can sharpen it correctly and clamp it to the tool post, can anyone offer any suggestions or guidance? Do you cut it in multiple passes, in a similar way to a metal thread?
I assume I¡¯m going to have to make and use some sort of a travelling steady. My idea is to clamp it in the chuck and use a small freely rotating chuck at the tailstock end.
I believe I can get a much better quality and accurate thread using the gears than trying to use it hand held - on a very long tool holder, the same as the ones on a wood lathe. I have to check but I think the wood for the screws is normally Beech, if that¡¯s relevant?
Thank you in anticipation.
David of Abingdon(UK)
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Re: Direct Reading cross feed dial.
Charles Kinzer
5:36pm? ?
The first sentence of that post ended with, "...another way to do it." I see the word "do" there. And even if it were not, I could certainly respond to the proposed idea whether anybody actually used it or even if just a pipe dream
They have use Direct Reading cross feed dial since the late 1950's on most lathes.?? I do not know why we see standard read on mini lathes today? Dave?
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Re: New topic ¡ª- Cutting a thread for a very old wooden clamp.
Great look but IMHO the metal screws are better!? ?Bill in Boulder
I did remember thread needs to be loose fit , corse thead and acme profile is best.
Dave?
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Re: Direct Reading cross feed dial.
The first sentence of that post ended with, "...another way to do it."? I see the word "do" there.? And even if it were not, I could certainly respond to the proposed idea whether anybody actually used it or even if just a pipe dream.
Charles E. "Chuck" Kinzer I
On Sunday, January 28, 2024 at 04:07:54 PM PST, davesmith1800 <davesmith1@...> wrote:
I like 90¡ã for picking up threads if need to redo.
Setting for shoulder work.?
Snap ring groves
Cooling fins
Some this could be done with a dial indicator or DRO.?
If compound is set at 29 to 30¡ã it makes harder to setup and have the carriage which not ideal.??
That is why I like direct reading dial on the cross slide only.?
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Re: Direct Reading cross feed dial.
I like 90¡ã for picking up threads if need to redo.
Setting for shoulder work.?
Snap ring groves
Cooling fins
Some this could be done with a dial indicator or DRO.?
If compound is set at 29 to 30¡ã it makes harder to setup and have the carriage which not ideal.??
That is why I like direct reading dial on the cross slide only.?
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Re: Direct Reading cross feed dial.
"I find numerous problems with the scheme of moving both handwheels like that for the purpose of making a 29.5 degree vector."
I could be wrong, but I didn't read it as him DOING it that?way or suggesting that we do it that way.? Rather, he was using vector analysis to CALCULATE how far the tool? move directly into the work when you advance it a certain amount on the diagonal and to work out a table of those values.
Mike Taglieri?
On Sat, Jan 27, 2024, 18:14 Charles Kinzer < ckinzer@...> wrote:
I find numerous problems with the scheme of moving both handwheels like that for the purpose of making a 29.5 degree vector.? That's all that is happening.? Two vectors at right angles combining to produce a vector at an angle.
First, the standard way doesn't require any trig at all.? You simply view the compound dial as direct reading.? Of course, this is an approximation because the sine of 30 degrees is 0.5 which would relate to exactly a direct reading.? the sine of 29.5 degrees is0.4924 so, technically, there will be an error.? But it is so small that it is typically ignored.? For example, if you had a 0.100 thread depth (pretty big thread in the mini lathe world at least) you get 0.0985" thread depth or a 1.5 thousandths error which is going to be within pretty much anybody's spec for a thread like that.? For typical smaller threads the error is in tenths because the error is about 1.5%.? How much absolute error is that for a 10-32?
Second, the primary purpose of the 29.5 degree compound is to have most of the cutting done on one edge and the other just as a skim cut.? By using the cross slide as part of creating the vector, that goal is substantially degraded as there will be too much cutting on the right edge (for typical right to left threading).? Since the scheme violates the primary goal, anyway, why not just go straight in and be done with it.
Third, you have to accurately set NEW positions on two handwheels.? That certainly increases the exposure for an error and a spoiled part.? Machinists typically don't want to do things a hard way when there is an easier one.
Charles E. "Chuck" Kinzer
On Saturday, January 27, 2024 at 11:17:39 AM PST, davesmith1800 < davesmith1@...> wrote:
Take a sharpie and cross out the numbers on your dial, then double them and write the new numbers in.
?
Brian?
Sharpie may last 30 seconds. I like the look of manufacture type dial. My second lathe had most of marks worn off and I used a center punch to fix it look tacky Dave?? Dave?
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Re: New topic ¡ª- Cutting a thread for a very old wooden clamp.
I did remember thread needs to be loose fit , corse thead and acme profile is best.
Dave?
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Re: New topic ¡ª- Cutting a thread for a very old wooden clamp.
Ok , huge brain fart over here , yea I have seen those . Looking at
that pic linked the wooden ones look like they have a same direction
thread full length of the screw ? I know on the ones I have with the
steel screw the thread's? change direction on each screw so each screw
has left hand & right hand threads . Lookin at one of mine some threads
run right into each other & on the other screw on the clamp there looks
like there's a break in the thread before they meet? on the screw .
Before & after lunch maybe ?
thanks for the pic's
animal
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On 1/28/24 3:19 PM, Gerald Feldman wrote: I believe the string was referring to ones that were all wood, like this:
Jerry F.
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Re: New topic ¡ª- Cutting a thread for a very old wooden clamp.
I believe the string was referring to ones that were all wood, like this:
Jerry F.
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Bill Williams
12:18pm? ?
I believe Martin Evans did one of these documented in "The Model Engineer" about 50 years ago.
It will work on few threads. Example? Lead screw with 8TPI It will work on 8, 16, 24 , 32 , 40 and 48 TPI THREAD cutting.?? In metric leadscrew 2mm It will work on 2mm, 1 mm and .5mm I can do that with a dog clutch just by using the haft nut. Dave?
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I believe Martin Evans did one of these documented in "The Model Engineer" about 50 years ago. His had an automatic tool retract and second clutch for a double speed return! Like a Hardinge production but DIY!? ?Bill in Boulder
On Sun, Jan 28, 2024 at 11:06?AM davesmith1800 < davesmith1@...> wrote: The CGTK dog clutch is shown here:
At end page he remove the clutch.
Also have program to calculate for threading dials.
Dave?
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Re: New topic ¡ª- Cutting a thread for a very old wooden clamp.
like these ?
thanks
animal
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On 1/28/24 12:01 PM, David Wiseman wrote: They are of the style of an engineers hand clamp but really HUGE in comparison and of course made of wood.
Best regards
David
On 28 Jan 2024, at 19:01, mike allen <animal@...> wrote:
?Are these clamps the " hand screw " clamps ? They have left & right hand
threads . I've never seen a set with wooden screws .
animal
On 1/15/24 11:39 PM, DAVID WILLIAMS via groups.io wrote:
Dear All,
I realise this is both part Mini lathe and part wood lathe. But to me the metal lathe part is more important. Hence my question to you all.
I have a couple of these old wooden clamps - probably antique. They are just like the metalwork ones we use, but much much larger. One has a severely damaged (external) threads.
I would like to try(?) and cut the replacement long wooden thread on my 7 x 12. So, I bought a second hand thread chaser on eBay. It¡¯s 6 TPI and according to the chart on the Little Machine Shop site - the gear set up is no problem on my imperial lathe.
[JFI it¡¯s Real Bull model purchased from Chester Machines (in the UK) some 20+ years ago. If that¡¯s at all relevant?]
The thread chaser cuts multiple threads at the same time and the tool (normally hand held I understand) needs to be held at ~ 90 degrees to the thread, unlike the usual angle for cutting one side of a metal thread. OR, if you are doing it by hand, do you angle the thread chaser so it cuts a series of slightly deeper threads. Thus the tool needs to be held in the tool post at a similar angle?
Assuming I can sharpen it correctly and clamp it to the tool post, can anyone offer any suggestions or guidance? Do you cut it in multiple passes, in a similar way to a metal thread?
I assume I¡¯m going to have to make and use some sort of a travelling steady. My idea is to clamp it in the chuck and use a small freely rotating chuck at the tailstock end.
I believe I can get a much better quality and accurate thread using the gears than trying to use it hand held - on a very long tool holder, the same as the ones on a wood lathe. I have to check but I think the wood for the screws is normally Beech, if that¡¯s relevant?
Thank you in anticipation.
David of Abingdon(UK)
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Re: New topic ¡ª- Cutting a thread for a very old wooden clamp.
They are of the style of an engineers hand clamp but really HUGE in comparison and of course made of wood.
Best regards
David
toggle quoted message
Show quoted text
On 28 Jan 2024, at 19:01, mike allen <animal@...> wrote:
?Are these clamps the " hand screw " clamps ? They have left & right hand
threads . I've never seen a set with wooden screws .
animal
On 1/15/24 11:39 PM, DAVID WILLIAMS via groups.io wrote:
Dear All,
I realise this is both part Mini lathe and part wood lathe. But to me the metal lathe part is more important. Hence my question to you all.
I have a couple of these old wooden clamps - probably antique. They are just like the metalwork ones we use, but much much larger. One has a severely damaged (external) threads.
I would like to try(?) and cut the replacement long wooden thread on my 7 x 12. So, I bought a second hand thread chaser on eBay. It¡¯s 6 TPI and according to the chart on the Little Machine Shop site - the gear set up is no problem on my imperial lathe.
[JFI it¡¯s Real Bull model purchased from Chester Machines (in the UK) some 20+ years ago. If that¡¯s at all relevant?]
The thread chaser cuts multiple threads at the same time and the tool (normally hand held I understand) needs to be held at ~ 90 degrees to the thread, unlike the usual angle for cutting one side of a metal thread. OR, if you are doing it by hand, do you angle the thread chaser so it cuts a series of slightly deeper threads. Thus the tool needs to be held in the tool post at a similar angle?
Assuming I can sharpen it correctly and clamp it to the tool post, can anyone offer any suggestions or guidance? Do you cut it in multiple passes, in a similar way to a metal thread?
I assume I¡¯m going to have to make and use some sort of a travelling steady. My idea is to clamp it in the chuck and use a small freely rotating chuck at the tailstock end.
I believe I can get a much better quality and accurate thread using the gears than trying to use it hand held - on a very long tool holder, the same as the ones on a wood lathe. I have to check but I think the wood for the screws is normally Beech, if that¡¯s relevant?
Thank you in anticipation.
David of Abingdon(UK)
|
Re: New topic ¡ª- Cutting a thread for a very old wooden clamp.
Are these clamps the " hand screw " clamps ? They have left & right hand
threads . I've never seen a set with wooden screws .
??? animal
toggle quoted message
Show quoted text
On 1/15/24 11:39 PM, DAVID WILLIAMS via groups.io wrote: Dear All,
I realise this is both part Mini lathe and part wood lathe. But to me the metal lathe part is more important. Hence my question to you all.
I have a couple of these old wooden clamps - probably antique. They are just like the metalwork ones we use, but much much larger. One has a severely damaged (external) threads.
I would like to try(?) and cut the replacement long wooden thread on my 7 x 12. So, I bought a second hand thread chaser on eBay. It¡¯s 6 TPI and according to the chart on the Little Machine Shop site - the gear set up is no problem on my imperial lathe.
[JFI it¡¯s Real Bull model purchased from Chester Machines (in the UK) some 20+ years ago. If that¡¯s at all relevant?]
The thread chaser cuts multiple threads at the same time and the tool (normally hand held I understand) needs to be held at ~ 90 degrees to the thread, unlike the usual angle for cutting one side of a metal thread. OR, if you are doing it by hand, do you angle the thread chaser so it cuts a series of slightly deeper threads. Thus the tool needs to be held in the tool post at a similar angle?
Assuming I can sharpen it correctly and clamp it to the tool post, can anyone offer any suggestions or guidance? Do you cut it in multiple passes, in a similar way to a metal thread?
I assume I¡¯m going to have to make and use some sort of a travelling steady. My idea is to clamp it in the chuck and use a small freely rotating chuck at the tailstock end.
I believe I can get a much better quality and accurate thread using the gears than trying to use it hand held - on a very long tool holder, the same as the ones on a wood lathe. I have to check but I think the wood for the screws is normally Beech, if that¡¯s relevant?
Thank you in anticipation.
David of Abingdon(UK)
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The CGTK dog clutch is shown here:
At end page he remove the clutch. Also have program to calculate for threading dials. Dave?
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Re: New topic ¡ª- Cutting a thread for a very old wooden clamp.
When doing wood use a light bedway oil.?
Wipe off every hour.
I use metal lathes for wood foundry patterns since 1960's.?
Never had a wood lathe
Dave?
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A dog clutch is used for threading in a number of high end lathes e.g. the Hardinge HLV-H.
The CGTK dog clutch is shown here:?
CGTK copied it from my site but it looks like he mis-understood how to engage the clutch which likely led to it failing.? Compare the first picture on my site:? ? to the first picture on the CGTK site and notice the spring on the rod which engages the clutch. This is missing on CGTK's version - this spring is important since it allows minimal force to be applied to the clutch while waiting for the spindle to rotate into position for the dog to engage.? Applying the full force of the trigger directly to the clutch likely caused the engagement mechanism to fail.? My dog clutch has not failed in the 15 years it has been in place, although it does need oiling every 3 or 4 years else it becomes slow to engage.
There is nothing wrong with using a thread dial for imperial or metric threading. But the original poster seemed to be preparing to build a metric thread dial which needs 3 interchangeable gears to cover all metric threads.? My point was that a dog clutch is relatively easy to build compared to cutting gears and making the numbered dial and the associated holder.? Plus the dog clutch works for imperial and metric. And it picks up the thread in one spindle rotation, no waiting for the dial to come around.
John
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Re: New topic ¡ª- Cutting a thread for a very old wooden clamp.
How do you keep from getting sawdust all over your oily ways, and every other part of the lathe with an oily film (i.e., all of it)?
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Re: New topic ¡ª- Cutting a thread for a very old wooden clamp.
If you haven't cut your thread already...
As a woodworker and machinist, I have used my metal lathe for wood parts fairly frequently.? If the threads are Acme or similar, think about mounting a Dremel (type) tool with a bit to cut the bulk of your threads before following with the chaser. Or a custom ground HSS bit or cutoff tool much narrower than the thread width to avoid grain tearout. You have to be extremely careful with a full dimension form tool with most woods at that grain orientation. If your wood is at all porous (lignum vitae wouldn't qualify) consider saturating the thread dowel with CPES, either commercial or thinning your own epoxy about 10% with alcohol. It will make the threads stronger and slipperier.
Joe
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