Author Topic: Making a Toolpost T Bolt  (Read 21060 times)

Offline Darren

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Making a Toolpost T Bolt
« on: February 24, 2009, 07:04:03 PM »
I wasn't going to post this as it's such a simple thing to make. But then I thought what the heck, let's not let this place get too quiet eh?

On my Smart & Brown lathe I use two tool holders and frequently swap between them. A while ago one of the T bolts broke so I've been making do with just the one. It's a real pain having to swap the bolts between the two holders all the time. So tonight I decided to do something about it.

An old bolt which is oversize to allow a good head size for the T bolt.



Skimmed the head down on both sides to the size of the T slot on the lathe, center drilled it and used my "patented" center punch as a center steady. Left and right handed tools used to turn the shaft dia.



Parted it off



Quick trim up on the miller to make the flats by using a collet block. Do one side and then turn the block over to do the other side.



Depth was set to take 3mm off both sides evenly



Looking good so far, need the bottom section of the shaft trimming to fit the upper part of the slot.



Used my parting tool to do this



Fits nicely



Snug as a bug



Unlike the other one I'm currently been using, though this does fit the other holder properly.



Well that's it for tonight, need to cut a thread and make a nut/lever to fit next.



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Offline Bernd

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Re: Making a Toolpost T Bolt
« Reply #1 on: February 24, 2009, 09:25:59 PM »
Nice use of an old bolt Darren. :dremel:

I've got a few of those laying around. Now I know what I can make out of them.  :thumbup:

Bernd
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Offline sbwhart

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Re: Making a Toolpost T Bolt
« Reply #2 on: February 25, 2009, 12:47:02 AM »
Good one Darren  :thumbup:

Like I tell my wife never chuck anything rusty out you never know what you can make it into.  :ddb:

Cheers :wave:

Stew


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Location:- Crewe Cheshire

Offline Stilldrillin

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Re: Making a Toolpost T Bolt
« Reply #3 on: February 25, 2009, 02:10:01 AM »
Nicely done....... Nicely shown, Darren...... :clap:

Thank you!  :thumbup:

David.
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Offline Darren

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Re: Making a Toolpost T Bolt
« Reply #4 on: February 25, 2009, 05:01:28 PM »
Thanks guys, I did wonder if it warranted the bandwidth being such a simple project.



Anyways, a little more done tonight. It's amaizing how this "quick" tasks seem to take several eves..... :poke:

The nut, we need a nut, pref one with it's own handle to save searching for the forever missing spanner and dropping it on the floor constantly.
Esp as I'm finding the floor seems to be getting further away these days. It's a long way down  :lol:



Chucked a length of steel stock, drilled it and tapped 10mm. Set the top slide over on the lathe to 10deg and put a taper on the end. Here you see it on the mill. I'm just about to put a flat on the taper.
The vice is set over by 10deg to match the taper.





Then it was center drilled, drilled and tapped 6mm for the handle.



Here's the handle....



The rusty bolt was trimmed up a little, head turned down and a short 6mm thread produced to match the nut.



Just need to cut the 10mm thread on the T-bolt now and it's all done



I say just !!
Been trying to do it tonight and gave up. 10mm is getting on the larger side for a die and the forces are getting too much to hold the part in my lathe without it slipping..!!

Oh bother !!

Never mind, I'll just have to do it on my precision lathe as a single point threading operation  :)

When I get it back that is, Bogs treasure den is a long way from here. Needs careful planning....oh the anticipation, can't wait !!!

 :ddb: :ddb: :ddb: :ddb: :ddb: :ddb: :ddb: :ddb: :ddb: :ddb: :ddb: :ddb: :ddb: :ddb: :ddb: :ddb: :ddb: :ddb: :ddb: :ddb: :ddb: :ddb: :ddb:
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bogstandard

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Re: Making a Toolpost T Bolt
« Reply #5 on: February 25, 2009, 05:17:52 PM »
Darren,

For the size of lathe you have, 25mm is starting to get large, 10mm should by done without even breaking into a sweat.

Have you turned the bar down to 10mm beforehand, as I have seen people trying to die down with the bar up to 2mm oversize. It don't work unless you are a gorilla.

John

Offline Darren

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Re: Making a Toolpost T Bolt
« Reply #6 on: February 25, 2009, 05:22:52 PM »
Hi John,

I turned the bar to 10mm dia to make a 10mm thread. But try as I might either the belt on the lathe slips ( the motor is held by an electrical brake) or the work slips in the collet.

I just can't seem to win on this. Using the 10mm tap gave the same probs, I only just managed to tap the thread on the nut.

I was thinking if I could make a spindle lock and go from there, ??

25mm, not a chance, not on this lathe as it is anyway.... :scratch:
« Last Edit: February 25, 2009, 05:24:46 PM by Darren »
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Offline Darren

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Re: Making a Toolpost T Bolt
« Reply #7 on: February 26, 2009, 05:11:39 AM »
Out of interest what sizes do you guys on here "power" tap or thread with taps and dies.

I find that threading under power works far more successfully than hand tapping. On the lathe I've done from 4mm - when the belt slips at around 10mm.
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Offline sbwhart

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Re: Making a Toolpost T Bolt
« Reply #8 on: February 26, 2009, 06:01:41 AM »
Hi Darren

I've never cut a thread under power not that I'm saying you shouldn't do it I just havn't had the balls to try. I've watched it done many times the last chap I saw do it was John and he made it look very simple. My new Sieg mill has a tapping function I'll have to get the curage up and try it.

I was talking to a chap at the model eng club and he was saying he taps down to 8ba using a cordless screwdriver, this seams a bit risky to me just think  :scratch: :- you've just spent a month machining up a cylinder, the last job tapping it for the cylinder covers and you break a tap

 :bang: :bang: :bang:

For a bolt

Regards your 10mm thread I don't know what you know about threads but basicly you have:- major dia, effective dia, minor dia:-

Major is the bigest dia:-  if you look at the thread specifications this is below the stated size I'e for a 10mm thread major will be say 9.8 ish

Effective dia is the half way size

Minor dia is the smallest or the diameter at the root of the thread.

For a nut this is the same but you have to think in reverese

Also from the specifications the sizes for nuts and bolts have built in clearances to allow fit.

A trick a lot of machineist do is to truncate the thread to make it easyer to machine for your 10mm thread you could machine your bar to say 9.7 this will leave a small flat on the top of the thread but it wont effect the strength of the thread to much, you can do the same trick when tapping by going the next size up with your tapping drill this reduces the load on the tap.

I hope this helps

Cheers
 :wave:
Stew
A little bit of clearance never got in the road
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Location:- Crewe Cheshire

bogstandard

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Re: Making a Toolpost T Bolt
« Reply #9 on: February 26, 2009, 06:25:22 AM »
With this new lathe Darren, I have tapped and die'd easily up to 12mm, and I suspect I could go a lot larger. At the moment, 8BA is the smallest I have done in internal and external. Normally I would use my vertical tapping stand for any smaller sizes.

For the smaller sizes, it is all to do with 'feel', larger, brute force.

When you have 40 or 50 holes to tap, you soon get over the fear of using power, otherwise you very quickly end up with sore and aching hands. But like everything, technique and lubrication are 99% of the job, and like Stew has said, get the material to the correct size first.

This chart I put in the downloads section gives you the acceptable range of drill sizes for threading. If the going gets tough, you can try a slightly larger size.

http://madmodder.net/index.php?action=downloads;sa=view;down=8

John

Offline Darren

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Re: Making a Toolpost T Bolt
« Reply #10 on: February 26, 2009, 07:17:43 AM »
Hi John,

What I usually do for tapping is drill to the thread size minus the pitch.
For external threading I usually turn to the outside diameter.

Thanks for the link to the chart, I've not seen that one before. Looks interesting, but confusing, eg it states a 1mm drill for a 10mm thread?
I'm obviously not understanding the chart properly  :scratch:

« Last Edit: February 26, 2009, 07:20:49 AM by Darren »
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Offline Darren

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Re: Making a Toolpost T Bolt
« Reply #11 on: February 26, 2009, 07:23:18 AM »
So if I understand you Stew, the outside dia I'm working to could be on the large size and we perhaps should be aiming just a touch under than  :scratch:
« Last Edit: February 26, 2009, 10:04:21 AM by Darren »
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bogstandard

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Re: Making a Toolpost T Bolt
« Reply #12 on: February 26, 2009, 10:25:11 AM »
Darren,

Just to explain the charts.

As you show rightly, you were using the correct chart, ie metric coarse.
As shown in pic 1 below, for 10mm, if you subtract the pitch (only in metric), that will give you the normal sized hole for tapping. Shown in the green circle on the next chart.

So if you follow the charts thru, and find the one for 10mm (marked red 1), for a super tight fit, you would use the size marked red 2, for a free thread you could use the bottom one marked red three. The last one will hold, and if you have some very tough material you could use that sized drill so you can get a thread in, but it won't be as strong as the ones higher up the chart.

You are quite correct in your assumption and what Stew has said, you can reduce the size of the bar to get an easier cutting thread, and still remain in safe limits. You could go say to  9.3mm, but that would give you a weaker thread. If I was doing it, I would most probably go as low as 9.7 or 9.8mm. But if possible stick to nominal size and open up the die to cut oversize first.

Look at the hole size spread on the tapping chart, that is 0.7mm (8.4mm to 9.1mm). You can use that spread for external cutting. So 10mm down to 9.3mm.
 
The smaller you go, the weaker the thread. But try to keep one or the other at the correct size otherwise you might find you get a lot of wobble. That is why if possible, you should always make the external thread second, and by cutting oversize to begin with (centre adjusting screw fully in), then compressing the die down for the next cut (slackening off the centre screw slightly, and nipping up on the two outer ones), you can get the external thread to fit perfectly in the internal hole.
 
John

« Last Edit: February 26, 2009, 10:46:32 AM by bogstandard »

Offline sbwhart

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Re: Making a Toolpost T Bolt
« Reply #13 on: February 26, 2009, 10:53:18 AM »
So if I understand you Stew, the outside dia I'm working to could be on the large size and we perhaps should be aiming just a touch under than  :scratch:

Thats it Darren  :thumbup: reducing the dia will reduce the load on the die and the torque you nead to turn it, you will be supprised how much easer a little of dia will make it.

Do an experiment turn up a length of bar in steps starting way under size and gradualy increase the dia ever 10mm then run a die up it .

Cheers
 :wave:
Stew
A little bit of clearance never got in the road
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Location:- Crewe Cheshire

Offline Darren

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Re: Making a Toolpost T Bolt
« Reply #14 on: February 26, 2009, 11:11:46 AM »
Thanks guys, all clear now, John again thanks for taking the time to explain the charts. I wasn't looking at them properly.

You raised a good point, "by cutting oversize to begin with (centre adjusting screw fully in), then compressing the die down for the next cut"

I'm using a solid die, now destined for the bin. Will search Ebay for a split type right now.

We are back to those cheap dies again!! Always grief with em it seems. Every new die I buy these days is the split type of high quality, but my 10mm isn't and it's a hex shape.

I must make proper die holder for the lathe too, another project coming up  :dremel:

Thanks again, I may be back on track now, well as soon as my new die comes.
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bogstandard

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Re: Making a Toolpost T Bolt
« Reply #15 on: February 26, 2009, 01:45:52 PM »
Darren,

You are not alone with the die nuts.

People just starting out buy these cheap tap and die sets from markets and other cheap outlets little knowing that they aren't for cutting threads, but for cleaning up threads that have already been cut. The only problem is that they are not very good for even doing that.
Correct HSS hex die nuts are usually a lot more expensive than a HSS split die, and are used a lot in the auto repair industry, for cleaning and repairing threads after the bolts or studs have been knocked about when removing them.

John

Offline John Hill

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Re: Making a Toolpost T Bolt
« Reply #16 on: February 26, 2009, 03:10:52 PM »
The Artful Bodger recommends using one of these as a tap handle!



A four jaw one grips the top of the tap nicely,  you get good feel for nearing the breaking point of those little taps,  you get a good feel for starting straight and of course your can really put the power on when required!
From the den of The Artful Bodger

Offline Darren

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Re: Making a Toolpost T Bolt
« Reply #17 on: February 26, 2009, 03:31:37 PM »
How do I fit that on the lathe?  :lol:


Nice idea though John, no struggling with that is there.. :dremel:
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Offline John Hill

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Re: Making a Toolpost T Bolt
« Reply #18 on: February 26, 2009, 03:49:31 PM »
How do I fit that on the lathe?  :lol:


Umm, I just move the tailstock out of the way and use the ratchet on the brace. :scratch:
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Offline Darren

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Re: Making a Toolpost T Bolt
« Reply #19 on: February 28, 2009, 09:57:15 AM »
A little pressie turned this morning, a 10mm die  :)

It has an unusual feature that I have not seen before? A little adjusting screw

Also note the lead in taper on the correct side



BUT, it has a bigger taper on the back/wrong side as well, I'm stumped, how do you thread up to a shoulder with this  :scratch:



The adjusting screw head



Anyways, I decided to set to and cut the thread, My bar was turned to 9.7mm but it was still tough going.
Then this happened



I just about bodged it and got the thread cut with the two halves, but it's not right. Even with the die closed tight the thread is still very tight.
But it works, just





I have emailed the seller with the pic of the broken die. I've never managed to break one before has anyone else broke one?

A tad disappointed
Darren
 :(



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Offline Stilldrillin

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Re: Making a Toolpost T Bolt
« Reply #20 on: February 28, 2009, 12:23:21 PM »
Darren,

OUCH!!!  :bugeye:

Did you use it as is? 

I don`t see a die holder.....:scratch:

You did hold it in a round die holder.... Didn`t you?

Lost teeth before. But I`ve never had one break like that.......

David.
David.

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

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

Offline sbwhart

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Re: Making a Toolpost T Bolt
« Reply #21 on: February 28, 2009, 01:54:03 PM »
Darren

Thats unusual to break a die like that I've never done it. How good a fit is it in the die holder, thers should be some play in it just enough to take the spring when you adjust it with the centre grub screw. Did it break under power ?, was it clogged with swarf that won't help.

Puzled  :scratch:

Cheers

Stew

A little bit of clearance never got in the road
 :wave:

Location:- Crewe Cheshire

Offline John Hill

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Re: Making a Toolpost T Bolt
« Reply #22 on: February 28, 2009, 02:47:28 PM »
Darren, my mate!  Dont feel bad about it, I am always busting things! :coffee:
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Offline Darren

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Re: Making a Toolpost T Bolt
« Reply #23 on: February 28, 2009, 07:23:11 PM »
Darren,

OUCH!!!  :bugeye:

Did you use it as is? 

I don`t see a die holder.....:scratch:

You did hold it in a round die holder.... Didn`t you?

Lost teeth before. But I`ve never had one break like that.......

David.

I used a proper round two handled die holder with the three adjusting screws.

I'm famous for breaking taps, but never a die before... :scratch:
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Offline Darren

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Re: Making a Toolpost T Bolt
« Reply #24 on: February 28, 2009, 07:26:19 PM »
Darren

Thats unusual to break a die like that I've never done it. How good a fit is it in the die holder, thers should be some play in it just enough to take the spring when you adjust it with the centre grub screw. Did it break under power ?, was it clogged with swarf that won't help.

Puzled  :scratch:

Cheers

Stew



It fitted as well as any other die I have. I held the work in the vice and did it by hand as it was slipping in the collet on the lathe. Not the collets fault as I was pushing it size wise due to needing one a tad smaller.

Plenty of lube and did the usual one turn forward half back thing.
You will find it a distinct help… if you know and look as if you know what you are doing. (IRS training manual)