Taper screw

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Taper screw

This topic has 20 replies, 9 voices, and was last updated 25 November 2009 at 16:43 by Gordon W.

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14 November 2009 at 10:18 #45052
Gordon W
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@gordonw
Does anyone have any ideas? I want to make a taper thread, like the end of a woodscrew, about 2″ dia X about 6″ long ,coarse thread, this will be for a log splitter, so OT a bit. My lathe is 8″ swing x 16″.No probs turning the taper, only thing I can think is to weld a spiral on then hand fettle, this is a one off so don’t want a huge amount of tooling to make. And no I don’t have a mill.
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14 November 2009 at 10:18 #4837
Gordon W
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@gordonw
14 November 2009 at 11:18 #45056
Circlip
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@circlip
Use Tailstock offset method for tapering and screwcut as normal. Use Ball end centres.

Regards Ian.
15 November 2009 at 11:34 #45081
Gordon W
Participant
@gordonw
Thanks for idea, just been reading other thread about taper turning, seems the offset will be way too much for this angle and depth of cut. It will need a pointy end, more or less. Just had idea,_ drill and weld in large coachscrew to get the sharp point, then offset tailstock and screw at shallower angle, will go and fiddle about. Where can I get a bell end center drill (mail order)?
15 November 2009 at 11:54 #45082
Ian S C
Participant
@iansc
Just off set the top slide,you’ll need to move it along a time or two,but you won’t have to set over the tail stock,and more important you won’t have to reset the thing after you’v finished(thats the important bit).As gordon says the angle is really too big for this method-setting over that is.IAN S C ps if you were in this part of the world no way would you buy a bellend center.
15 November 2009 at 13:57 #45089
Terryd
Participant
@terryd72465
Just a bit of information. A traditional woodscrew does not taper. The crest of the threads are parallel, it is the core that tapers.

TD
15 November 2009 at 17:21 #45103
chris stephens
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@chrisstephens63393
Hi Gordon W,

I seem to recall that ARCEURO sell them, but be very careful when using theirs. The small pilot is very small and will break easily, don’t ask, don’t be tempted to drill normaly. The technique is to “peck” drill, this way the swarf will not jam up the flutes quite so quickly. It is good practice to do this with all centre drills! Saves a lot of breakages.

chriStephens
16 November 2009 at 14:48 #45156
Gordon W
Participant
@gordonw
Thanks for the info. will buy bell end cd for other job. For interest the best ideas so far are 1-turn taper on t/slide and weld spiral on. 2-hand turn the screw thread, never tried that, sounds scary.
16 November 2009 at 15:13 #45158
charadam
Participant
@charadam
Could one of these in the 1 1/2″ diameter form the basis?

http://www.portlandbolt.com/products/bolts/square-head-lag.html
16 November 2009 at 23:13 #45173
JohnF
Participant
@johnf59703
Do you have a taper turning attachment for your lathe? If so the job is easy — just turn your taper with the top slide set at 90deg to the bed [or 90deg to the taper] then screwcut as normal with the taper turning attachment still engaged.
17 November 2009 at 08:58 #45183
Ian S C
Participant
@iansc
Gordon what pitch is the thread?I would have thought it would be too coarse to cut on the lathe as a normal thread ie 20 to 30mm or 1 per inch or more.IAN S C
17 November 2009 at 09:44 #45184
Gordon W
Participant
@gordonw
Hi, charadam-thanks for that link, one of those would maybe work, will go down the pub and see if anyone can get one.. Don’t have taper attachment, one day will make one but for a one off seems a lot of work. Pitch I,m guessing at 2 or 3 per inch but this is the experimental bit.
17 November 2009 at 10:21 #45187
Ian S C
Participant
@iansc
Will your lathe cut that?My 1324 BH Taiwanese lathe will only go to 4tpi,I thought that was fairly coarse,I’v used that to make some ordenary wood screws somewhere about 1/4″ dia.
17 November 2009 at 11:33 #45191
Gordon W
Participant
@gordonw
IanSC:_hello,I’ve just been in the shed counting changewheels, should be able to cut 10mm pitch if the wheels will fit in the banjo, but I’ve got the toothache and all brain power has stopped. Will try again in a couple of days.
17 November 2009 at 23:15 #45243
charadam
Participant
@charadam
Posted by Gordon W on 17/11/2009 09:44:45:

Hi, charadam-thanks for that link, one of those would maybe work, will go down the pub and see if anyone can get one.. Don’t have taper attachment, one day will make one but for a one off seems a lot of work. Pitch I,m guessing at 2 or 3 per inch but this is the experimental bit.

Gordon,

Strange story – i was mowing the lawn a few days after the Post Office had renewed a telephone pole in my garden. Nearly ran over a 1/14″ sample of the coach screw (it apparently is, or was used on the past, to secure footsteps to large diameter poles) that they had discarded on my patch.

I didn’t know such beasts existed until then – and if I can find the item in my scrap pile, your are very welcome to it!

ATB,

Charles
18 November 2009 at 10:09 #45250
Steve Bell 1
Participant
@stevebell1
Might sound a very poor way of doing it but it’s worked in the past for me, and comes from something my father read.

Turn the taper as per usual then undo the retainng for the cross slide screw, so the cross slide can be pushed backwards and forward by hand.

Set up for screw cutting as per normal and use a light spring to apply the force to pull the cutting tool onto job. A long spring is needed if the diameter of the taper changes a lot so as not to put excessive pressure on the larger diameter.

When I did it I used an elastic band (!) and got surprisingly good results.

Steve
18 November 2009 at 10:43 #45254
Ian S C
Participant
@iansc
Charadam,if the telephone pole hardware in uk is the same as here in NZ I think you will find it similar to wrought iron ie if you cut it up you find layers of slag inclusions.I often use old bolts,and other junk,and have tried pole hardware,including climbing bolts(screwed in side of pole to climb for servicing),usually can’t use the item because of the inclusions.Some times you can get coach screws either hex or square head ungalvanised,ie black like machine bolts,these are mild steel.IAN S C
19 November 2009 at 10:22 #45321
Gordon W
Participant
@gordonw
Charadam:_ strange story, have just been at the back of one of my sheds to clear rats, and uncovered a rotten wooden box containing old ex telephone/electric pole fittings inc. large coachscrew, very heavy galvanising on all. Thanks for the offer tho’. SteveB, like the idea,but with deep threads might be too much, wonder if a taper guide at back of slide will work? Sort of hand held taper turning atttachment. Any way this idea will stay just that until I do a few calcs., (and paint the bathroom)
19 November 2009 at 11:09 #45324
Ian S C
Participant
@iansc
I’m a bit far away,but I’v got some wood screws here from the nearby railway line,used for screwing the tracks to the wooden sleepers,aprox 2 threads to the inch.IAN S C
24 November 2009 at 21:44 #45553
Nigel McBurney 1
Participant
@nigelmcburney1
Hi Woodsplitter screws have a buttress thread,they are hardened and difficult to cut,if driven by tractor pto they need to be l/hand,the point is detachable /replaceable to cope with wear and the thread is finer on the detachable point about 2mm pitch,the body part is threaded coarser at about 3mm.the only sensible way is spiral milliling but even the universal dividing head will will run out of gears,a short lead attachment is essential and in fifty years I have not even seen one of these attachment though they are illustrated in most older tech books,if the thread is worn they will not work.so do not bother unless the screw can be hardened,I know i have tried the points cost over £70 and the local woodman has asked me many times if I can make them cheaper,for home made splitters go hydraulic,screw splitters are peferred in the trade as they are quicker,hydraulic are more reliable . nmcb
25 November 2009 at 16:43 #45578
Gordon W
Participant
@gordonw
Thanks Nigel,I’ve just been to look at a tractor/hydrualic screw splitter and of course you are right.My idea was to make one electrc motor/flywheel drive but looks like a non-starter. But I’ve been reading Milling in the lathe, Tubal Cain. In there is description of spiral fluting and etc. using a cutter head in the toolpost, this might be adaptable to scerw cutting 2 or 3 start threads on a taper, but will have to wait.
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