¾” 4TPI lead screw nut

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¾” 4TPI lead screw nut

This topic has 8 replies, 5 voices, and was last updated 31 May 2019 at 08:45 by simon Hewitt 1.

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23 May 2019 at 15:28 #410599
simon Hewitt 1
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@simonhewitt1
Does anyone know where I could get a ¾" 4TPI lead screw nut? Outside dimensions not important, its to fit an old pillar drill, the table lift is by lead screw and it has stripped out the thread in the table carrier. Thanks

Simon
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23 May 2019 at 15:28 #29919
simon Hewitt 1
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@simonhewitt1
24 May 2019 at 00:42 #410676
John Reese
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@johnreese12848
It is possible to single point a 3/4-4 thread. I used either a 5/8" or 1/2" boring bar with a very short tool bit. There was not sufficient clearance to withdraw the tool from the hole. I had to back off the cross slide a few thou and wind the tool out of work. I did it on a 13" lathe and it took many, many spring passes to finish the thread. I am not sure how well a smaller, less rigid lathe would handle the job.
24 May 2019 at 07:23 #410691
Chris Evans 6
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@chrisevans6
Have you looked at the prices from the lead screw suppliers? It may be quicker and cost effective to buy a length of lead screw and a nut, for rise and fall does the pitch matter ? I did my lathe cross slide for sub £50 and have enough screw for three replacements. Consider going trapezoidal/metric it can be cheaper.
24 May 2019 at 20:27 #410815
simon Hewitt 1
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@simonhewitt1
Thanks Chris Evans – I think I will go this route. The screw is almost exactly 1 M long, and as you say, pitch is not critical, it just has two bevel gears and a winding handle. I am tempted to go for a ball screw and lead, and an electric motor, with an up/down switch, just for fun. Also I am not certain it is an Acme thread, looks like a square thread, but its difficult to see clearly until I pull it out. And it weighs a lot!, must be > 150kg.
30 May 2019 at 14:29 #411705
Zane Crowther
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@zanecrowther67531
Hi,

There are lots of trapezoidal screws and corresponding nuts online. Maybe have a look at these: **LINK**

Zane
31 May 2019 at 06:49 #411840
Michael Gilligan
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@michaelgilligan61133
Posted by simon Hewitt 1 on 24/05/2019 20:27:53:

The screw is almost exactly 1 M long, and as you say, pitch is not critical, it just has two bevel gears and a winding handle. I am tempted to go for a ball screw and lead, and an electric motor, with an up/down switch, just for fun. Also I am not certain it is an Acme thread, looks like a square thread, but its difficult to see clearly until I pull it out. And it weighs a lot!, must be > 150kg.

.

Presumably this is the drill pictured in your Album, and nicely illustrated here: **LINK**

http://lathes.co.uk/denbigh-drills-page2/

… If so, I am sure you are thinking along the right lines

MichaelG.
31 May 2019 at 08:42 #411862
simon Hewitt 1
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@simonhewitt1
What a great illustration. Mine is newer than that with the motor behind the column and modern style multi-sized V pulley, but the main column and the table adjust are exactly the same.

Chinese balls screws are remarkably cheap and I have a windscreen washer motor that will probably do, I will post a photo when complete.
31 May 2019 at 08:45 #411864
simon Hewitt 1
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@simonhewitt1
In fact, looking at the lathes site, mine is the K.1.A series 2 on page 2 here
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