Author Topic: Lathe chuck backstop  (Read 20780 times)

bogstandard

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Lathe chuck backstop
« on: August 23, 2009, 02:39:45 PM »
How many times have you had to make a load of bits on the lathe all to the same length.

PITA isn't it?

What you need is to push the bar back into the chuck until it comes to a dead stop, then once tightened, you can use one setting to cut the face, and every one after that will be the same length, within a thou or so.

So this is how I went about making my chuck backstop.

This is about one of the cheapest but best bits of kit you can make for your lathe, and if used correctly can save you hours of machining time, and reduce recycling to zero.


First off, I got a soft end blank morse taper to fit my machine, theses are only a few squid each and I usually have a couple in stock of the two sizes my lathe uses, just in case a job like this comes along. If you want to go the cheapskate and difficult way, and make your own, that is up to you. To me, for the cost of them, they are just not worth making.
The normal sizes used for lathe spindles nowadays is either 2 or 3 morse taper.

http://www.arceurotrade.co.uk/Catalogue/Blank-End-Arbors




The soft end needs to be reduced so that it will fit thru the smallest centre of your chuck range into the spindle without having to remove the chuck. The easy way is just to reduce it down to where it meets the taper.




With the chuck off the machine, mount it into the spindle nose.




Turn down the soft end until it is the same size as the largest part of the taper. As you can see, it will now easily go into the smallest part of my chuck, the centre hole in a 5C collet.




Drill down the centre as far as you can go with a tapping drill of your choice. I am using an 8mm thread, for a 2MT I would suggest 6mm or 1/4" thread.
You will most probably find you can only drill down the length of the softened end, which will give you about 3/4" adjustment on the stop length.




Then tap down as far as you can go.




I used an 8mm coachbolt, but you could use almost anything, even threaded rod if you have it. Screw it as far in as it will go, and tighten up the locknut.




I have removed the chuck jaws to show you what is going on.
All power off the machine, stick a rag into the spindle end and push it all the way thru the spindle with a stick. You do this every time you fit anything into the morse taper in the nose, just to get rid of debris in there that will stop the MT seating properly.
Feed the backstop thru the chuck and get it seated in the spindle.




This is bit of a hoptical dillusion. You need to mark up the screw length just before it would hit the back of the jaws. So if the jaws are tightened up, they won't touch the backstop screw.




Cut the screw to marked length, and face it off.




This shows how the screw fits, it isn't screwed all the way in just so I could get this angled shot. Normally you would take the stop out when not in use, and when you fit it, you adjust it to length to push your part back to, ensuring the locknut has been tightened before mounting it into the spindle..




As mine is, it can only be used with parts that are larger than 8mm and longer than about 25mm (1"), that is because it isn't completely finished.
I will put say a 4mm (5/32") thread in the very end of the 8mm adjusting screw, and make up little adapter noses for smaller material sizes. Just as I have done for the 5C collet backstop in the top of the picture. You soon end up with all sorts of ends that you keep in a little box for almost any occasion.
The bolt at the bottom could be faced off and used for a backstop for material having a hole thru it, say a bored cylinder. You just have to use your imagination a bit.



If you don't understand anything, just ask.

I can't give any machine specific answers, because unless it is the same as mine, I just won't know. But ask away anyway, because someone on here will know what you are talking about.


Bogs


Offline arnoldb

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Re: Lathe chuck backstop
« Reply #1 on: August 23, 2009, 03:50:51 PM »
Thanks Bogs  :clap: - this bit of kit is on my to-build list as well.
Quote
If you want to go the cheapskate and difficult way
  :lol: - wish I could do it quick 'n easy, but being in a "sort-of-out-of-the-way" location I'll just have to be a cheapskate  ::)
Quote
hoptical dillusion
  :lol: :lol: :lol: :lol:
 :beer: Arnold

bogstandard

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Re: Lathe chuck backstop
« Reply #2 on: August 23, 2009, 04:18:39 PM »
Arnold,

It must be very difficult for people like yourself living out in the 'stix'. I just order something one day, it is here next morning.

But if you look at the other side of things, you will learn a lot more because you have to make most of the stuff yourself.

I used to make all my own tooling and bits at one time, and even now, when I see a bit of scrap, all I can see is what it can be used for or what can it be made into.

Bogs

Offline spuddevans

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Re: Lathe chuck backstop
« Reply #3 on: August 23, 2009, 04:41:19 PM »
Thanks for posting this John  :thumbup:

Yet another project to add to the ever growing "Essential projects" list  :proj:


Tim
Measure with a micrometer, mark with chalk, cut with an axe  -  MI0TME

Offline NorthOf40

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Re: Lathe chuck backstop
« Reply #4 on: August 23, 2009, 09:01:31 PM »
Thank you John :thumbup:
Jim
Sometimes I wonder whether the world is being run by smart people who are putting us on or by imbeciles who really mean it. – Mark Twain

Offline Stilldrillin

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Re: Lathe chuck backstop
« Reply #5 on: August 24, 2009, 02:27:02 AM »
Nicely done John.  :clap:

Thank you!  :thumbup:

David D
David.

Still drilling holes... Sometimes, in the right place!

Still modifying bits of metal... Occasionally, making an improvement!

bogstandard

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Re: Lathe chuck backstop
« Reply #6 on: August 24, 2009, 02:27:45 AM »
Glad if it helps someone guys.

Just a note about when you buy blank end arbors for doing this job.

Go for the longest soft area, the diameter doesn't matter, as you cut most of that away anyway. That will give you the longest adjustment for the screw in rod.

If you want to make them yourself, then old large drills with a MT fitting can be utilised very well. The fitting is usually fairly soft anyway, just cut the drill part off. You are not worried about having a hardened MT fitting, or being very accurate, as it isn't doing any driving, just make sure it is cleaned up to a smooth finish. Heating to red hot, hold it there for a minute or so, and then letting it cool down slowly should soften it down a lot, allowing you to drill and tap to a good depth.

Bogs

Offline Gerhard Olivier

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Re: Lathe chuck backstop
« Reply #7 on: August 24, 2009, 03:38:47 AM »
Thanks Bogs

Ad that to the sadle stop and I can see how to do this.
Nice explication

Gerhard
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Offline 28ten

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Re: Lathe chuck backstop
« Reply #8 on: August 24, 2009, 03:40:53 AM »
Very useful, thank you. It will save me a lot of time when I have to make up axles. :thumbup:
If it ain't broke, i'll fix it until it is.

Online John Hill

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Re: Lathe chuck backstop
« Reply #9 on: August 24, 2009, 04:22:56 AM »
I know, I know, there is always a dumb one but I am thinking this is only practical for quite short pieces? :scratch:
From the den of The Artful Bodger

Offline arnoldb

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Re: Lathe chuck backstop
« Reply #10 on: August 24, 2009, 05:23:56 AM »
Arnold,

It must be very difficult for people like yourself living out in the 'stix'. I just order something one day, it is here next morning.

But if you look at the other side of things, you will learn a lot more because you have to make most of the stuff yourself.

I used to make all my own tooling and bits at one time, and even now, when I see a bit of scrap, all I can see is what it can be used for or what can it be made into.

Bogs

Thank you for understanding John  :bow: , and yes, I came to the same conclusion regarding the learning.  Anyway, the satisfaction I get out of making things is priceless.

Kind Regards, Arnold

bogstandard

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Re: Lathe chuck backstop
« Reply #11 on: August 24, 2009, 06:12:20 AM »
John,

Quote
I know, I know, there is always a dumb one but I am thinking this is only practical for quite short pieces?

You are quite right, but most of the time, it is short pieces that are being made.

But there is nothing stopping you making one for the other end of the spindle, and working from that. Some sort of taper locking and a large faced end going forwards. In fact, if yours is the same as mine, it has screw threads in the back end of the spindle, that are I think, something to do with gunsmithing and boring barrels. I am looking to put them to use sometime for a turning handle and long bar precision support.

John

Offline ozzie46

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Re: Lathe chuck backstop
« Reply #12 on: August 24, 2009, 06:28:57 AM »


  Thanks John, I have an mt taper from my failed homemade collet project ( to much runout on collets) that I can use.

  Thinking this could be used to make the top end support rods for your Paddleducks engine the same lenght.

  Ron

bogstandard

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Re: Lathe chuck backstop
« Reply #13 on: August 24, 2009, 06:55:38 AM »
Ron,

That is exactly the sort of jobs it is used for.

I use a backstop in my 5C collets all the time, but as I have explained before, they are not super accurate because the position can be altered by how much you tighten the collet. This type is spot on, because once it is locked into the spindle, it is going nowhere, and once your saddle is locked, you can just face up to the same length time and again.

John

Offline ozzie46

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Re: Lathe chuck backstop
« Reply #14 on: August 24, 2009, 03:16:39 PM »


 Thanks John, Good to know.


  Ron

Offline John Rudd

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Re: Lathe chuck backstop
« Reply #15 on: November 09, 2009, 05:31:32 PM »
Just read this........ :doh:

Boy I could have done with this thread when making up the spacers for my mill X axis mod....(I'll post pics when its complete...dont hold your breath! )

Having to cut several ( well 3..) spacers to the same length was a pita....

Thanks Bogs for sharing
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Offline websterz

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Re: Lathe chuck backstop
« Reply #16 on: November 10, 2009, 08:37:59 AM »
This is bit of a hoptical dillusion.


Bogs

Is that anything like a fig newton of the imagination?  :D
"In the 60's, people took acid to make the world weird.  Now the world is weird and people take Prozac to make it normal."
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Offline framey

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Re: Lathe chuck backstop
« Reply #17 on: November 11, 2009, 04:54:03 PM »
would it be possible for someone to post a pic or 2 of how this actually works please  :(
i can see the idea behind it but havent got a clue on how to use it lol

how would you actually insert the material?
do you cut it roughly to length first?
 :scratch:
« Last Edit: November 11, 2009, 04:56:55 PM by framey »

Offline CrewCab

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Re: Lathe chuck backstop
« Reply #18 on: November 17, 2009, 07:21:06 PM »
Is that anything like a fig newton of the imagination?  :D

Similar .......... and also closely related to "a figment of your emancipation"  :bugeye: ...............   :clap:

Framey, it's pretty straightforward, the bolt in the centre is adjusted and tightened with the locknut so when you insert a piece of stock it hits a "stop" ......... then part off at whatever length you require, once you are happy with the stop and lathe tool position just lock off the carriage and each piece you put in the chuck, push up to the stop and then part off will be exactly the same  :dremel: ........... hth but shout up if you want a some more info ........ as for adjusting / tightening either do it with the chuck off or use a hollow socket wrench and cut a screwdriver slot in the end of the adjusting bolt.

John .......... nice write up  :thumbup: as ever  :beer: ........... and a useful bit of kit, I'm ordering a blank MT3 arbour as I type ............. my own to do list must now be almost as long as the one SWMBO keeps adding things to  :smart: ............. OK lets be honest here guys the "other" list is probably 10 times longer than mine ........... and as "youngest son" has just bought a house ........ "In need of modernisation" ........... I believe said list will multiply 3 fold shortly  :(

So I may be absent for some years time  :bang:

 :coffee: CC

Offline framey

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Re: Lathe chuck backstop
« Reply #19 on: November 18, 2009, 03:01:02 PM »
maybe its easier to use than imagination doing it lol
one of those ahhhhhhhhhhhhh moments