By continuing to use this site, you agree to our use of cookies. Find out more
Forum sponsored by:
Forum sponsored by Forum House Ad Zone

HTS Bolts

All Topics | Latest Posts

Search for:  in Thread Title in  
1 2 3 Next > Last >>
John C31/12/2009 09:55:15
273 forum posts
95 photos
I needed a couple of holding down bolts and thought I would turn down the heads of HTS bolts to fit the T slolts, and then part off to length.  Turning the heads was no problem (nice and thin, so they go before the cross slide - thanks Meyrick) but the parting off was a different matter.  I assume that the shafts are hardened but the heads are soft, although I thought that an indexed carbide tool should still be able to cut the shafts.
 
I decided to anneal the shafts and had them to red heat for a few minutes each. The '1 hour per inch of diameter' rule definitely applies, as they were still very hard!  One thought I had was the effect on me of the zinc coating burning off, but a quick look on t'interweb indicated that my fears of poisoning were groundless.
 
So they've been in the woodburner stove all night - I shall see what the results are later.
 
Any thoughts or points on machining HTS bolts?
 
Thanks,
John
KWIL31/12/2009 10:11:04
3681 forum posts
70 photos
It is not clear whether you intend to shape the heads to fit the T slots? Why use HTS for this job? 
I have previously use HTS bolts to provide spindle material for a Quorn and Quick Step Mill, turning it with normal idexable insert tooling without undue difficulty.

Edited By KWIL on 31/12/2009 10:32:42

John C31/12/2009 10:49:23
273 forum posts
95 photos
I used HTS because they happened to be on the shelf!  The bolt heads, once thinned, fitted the T slots although with less bearing surface than a non-hexagonal head would have. 

Edited By John Corden on 31/12/2009 10:49:58

KWIL31/12/2009 11:32:23
3681 forum posts
70 photos
I am very careful about what I use in the T slot, I prefer the proper t-nuts because I have seen the damage done by others to the underside of the  "T"  by too small a bearing area.
John C31/12/2009 11:54:27
273 forum posts
95 photos
Yes - very good point.  A future project is to make a stock of T nuts and T bars. Perhaps I should do that sooner rather than later!
John
Circlip31/12/2009 12:03:54
1723 forum posts
8.8 HTS bolts are ideal for making crank shafts and the like for our toy engines, but as Kwil has stated, not a good idea for tee bolt conversion. If left un-annealed, you stand a good chance of breaking the lips of the tee-slot off and if annealed, why didn't you use M/S??
 
  Made some Tee-nuts for mine using a tough square section bar the A/F size slightly GREATER than the slot max width and turned a spigot of a diameter equal to the min slot width. Drill and tap to suit and use studs. For same sized bolts I turn the spigot to whatever length required and thread the end. You can then file the heads to a smooth fit on the width.
 
  The Head should Always fill the tee slot.
 
  Regards  Ian
Alan Worland31/12/2009 13:33:03
247 forum posts
21 photos
I use similar 'T' nuts to Circlip and use long bolts where I can, the bolt is wound through the T nut until the bolt end touches the base of the slot, jacking the nut up which secures it in place and thus stops it/them moving around - which I find they always do at the wrong moment!
KWIL31/12/2009 14:05:04
3681 forum posts
70 photos
I know a lathe supplier who observed to me, if people use non OEM T-nuts, I end up selling them a new T slotted .....  The moral being, they must fit properly and be of the right size, Circlips got it right .
 
The use of a nut + washer to pull up the T-nut squarely is perhaps a better way of ensuring that the undersides remain in place and the T-nut+bolt combination does not slide about
david pilkington 131/12/2009 14:43:22
1 forum posts
Tee Nuts should NEVER have thro hol;es, as there will be a risk of breaking the CI tee slot in the bed, if the nut on the bolt becomes bound or tight and the tightening is then in the tee nut.and so jacking it back up and breaking the bed of the machine
Alan Worland31/12/2009 15:29:09
247 forum posts
21 photos
Good point, but I think a bit of common sense helps? I have never had probs
Circlip31/12/2009 17:21:05
1723 forum posts
DP1, "Studs" have a plain part between the threads, so you can only screw into the head as far as the thread will let you, - make em shorter and you don't NEED any common.
 
  Regards  Ian.
mgj31/12/2009 18:12:07
1017 forum posts
14 photos
I agree with Kwil Circlip and others. I think the practice of pushing a bolt through a tee nut to lock on the bottom of a groove is unwise.
 
I bought  - I think they are Zenit items - 12mm threaded teenuts (which are soft). I got 10 for 86p plus vat.
 
I bought a whole load of studding, but even studding is medium tensile. I cut lengths of studding and then screwed them into the tee nuts and ring welded.
 
Any tee nuts I make I make out of soft MS, and as KWIL suggests, I always make them a good size to fil the slot and give max bearing area. Not too tight because they can stick on swarf, but sensibly full.
 
Of course, it doesn't matter if you are clamping a vice down, because such a joint puts the bed in compression, but one wants to be a bit less than ham fisted if one is not pulling against a flange and the table is in tension.
Tony Pratt 131/12/2009 19:14:48
2319 forum posts
13 photos
Hi John, pushing a bolt through the tee nut is indeed unwise, if the stud is damaged on the threaded portion which your clamping nut is on [a lot are], when you tighten up,the stud will try to jack the tee nut higher in the slot rather than clamping the job.
In many years of commercial machining I can't recall ever using high tensile studs or bolts. If you are applying enough force on one clamping location to need high tensile studs etc. you will be seriously compromising the tee slot itself. I have always found the more clamps you can apply the better.
 
Happy new  year to you all,
 
Tony
Circlip01/01/2010 00:33:41
1723 forum posts
Well Tony on a purely personal note, nowt wrong with using HTS studs cos they don't stretch and distort like M/S, far more impotant is teaching the uninstructed to clamp PROPERLY. Bolts to the FRONT of the clamp slots, Know what I mean??
 
         Regards  Ian.

Edited By Circlip on 01/01/2010 00:34:15

mgj01/01/2010 09:06:52
1017 forum posts
14 photos
And only ever 3 clamps - like 3 legged stool as opposed to a 4 legged table. 3 clamps won't rock.
 
Going back to  the original question - how to machine HT. reasonably slowly, not too much rake, lots of coolant and tailstock support (the latter especially when parting off, because it quite often pops up towards the end of the cut, rahter than dropping off as it should - helpfully that just chips the tip off the tool.
John C01/01/2010 10:00:27
273 forum posts
95 photos
Happy New Year one and all.  Thanks for all the replies!  I must now confess - the only reason I was using HTS was because I picked up the first bolts I came to to off the shelf, and only after the failed cutting attempts did I see they were HTS.  So - I shan't be doing that again!!
 Incidentally, putting them in the fire all night had the desired effect, but too much so - they had the properities of sticks of lead!  I shan't be tempering them as the correct option - i.e. do it right in the first place - has now become the quickest and easiest.  Here endeth the lesson.
 
John
Tony Pratt 101/01/2010 10:42:50
2319 forum posts
13 photos
Hi Ian, nothing wrong at all with using HTS bolts, as you say mild steel does tend to stretch a tad ! I know exactly what you mean about clamping correctly, it's easy to do the wrong thing if not shown the correct way. I have also seen plenty of so called skilled men create some appalling lash ups, but that's another story.
 
Tony
Frank Dolman01/01/2010 12:28:14
106 forum posts

       Well, Meyrick I was not surprised by your reply to my question about
   torque on clamp bolts under the 'table cover' thread.  It all seemed
   sensible but now we have a couple of contributors saying that MS bolts
   stretch too much!  Even baby 1/4" bolts would need fair old torque to
   stretch enough to affect their clamping surely?
        Are these contributors perhaps some of the sailors the Admiralty
   found stripping anything under 1/2" Whit?
Tony Pratt 101/01/2010 13:21:45
2319 forum posts
13 photos
Hi Frank, I don't believe any one said that MS bolts "stretch too much". From my old college days I think I am right in saying that any bolt will stretch when put under load, MS more than HTS for the same load, they will return to their original length once the load is removed unless they have been taken past their elastic limit. I await the definitive answer on this one as it's been a fair few years[too many] since I was an apprentice.
Tony
Nicholas Farr01/01/2010 13:34:14
avatar
3988 forum posts
1799 photos
All bolts should streach a tad during thier application, all be it by a few microns. This is how they work. You can imagin them as solid springs, but as with springs they all have different tensile strengths. When springs are streched beyond thier design limit, that is thier yield stress, they will not return to the original length. The same is true with bolts. HTS bolts will streach less than soft bolts, but will have a much higher yield stress. I would not recommend any HTS bolt higher 8.8 to be used in T slots as the yield stress of 8.8 bolts and above would probably be above that of the T slot. A grade of 4.6 would probably suffice in most cases, where as soft MS bolts do seem to keep on streaching and the threads distort with continued use. I also agree that using bolt heads in T slots is asking for trouble as well as allowing studs to protrode through T nuts. Nick
1 2 3 Next > Last >>

All Topics | Latest Posts

Please login to post a reply.

Magazine Locator

Want the latest issue of Model Engineer or Model Engineers' Workshop? Use our magazine locator links to find your nearest stockist!

Find Model Engineer & Model Engineers' Workshop

Sign up to our Newsletter

Sign up to our newsletter and get a free digital issue.

You can unsubscribe at anytime. View our privacy policy at www.mortons.co.uk/privacy

Latest Forum Posts
Support Our Partners
cowells
Sarik
MERIDIENNE EXHIBITIONS LTD
Shopping Partners
Subscription Offer

Latest "For Sale" Ads
Latest "Wanted" Ads
Get In Touch!

Do you want to contact the Model Engineer and Model Engineers' Workshop team?

You can contact us by phone, mail or email about the magazines including becoming a contributor, submitting reader's letters or making queries about articles. You can also get in touch about this website, advertising or other general issues.

Click THIS LINK for full contact details.

For subscription issues please see THIS LINK.

Digital Back Issues

Social Media online

'Like' us on Facebook
Follow us on Facebook

Follow us on Twitter
 Twitter Logo

Pin us on Pinterest

 

Donate

donate