Hobson H7 lathe

[parvum]

Hi all, I have recently aquired a Hobson H7 lathe to upgrade my much loved ML4, the H7 is a geared head  and has more levers than the basic ML4 Can anyone advise as to the corrct use of the change speed levers on the headstock please. This seems to be a very rare lathe and a previous baboon has broken out one of the T slots on the cross slide.Does any one have a suggestion for a repair or replacement? according to Tony's lathe page these were a Myford clone but would a cross slide from an  ML7 fit? Thanks for any replies

Paul

[hermetic]

I'm sure someone will have some ideas, can youi post some pics of the damage. Looks like a well made machine.
Phil

[RobWilson]

Any photos of your new lathe Paul 


The saddle dose look like a copy of the ML7 .

Rob

[nrml]

I don't know if this will be applicable in your case, but this  damaged T slot repair is the simplest and most elegant solution I have seen. http://www.neme-s.org/shapers/columns/shaper_column_29.html

[nickle]

I agree with nrml but with the further refinement of incorporating the idea vtsteam described in his new lathe thread(http://madmodder.net/index.php/topic,10542.75.html reply #90) by making your own countersunk fasteners that will protrude above the repair prior to final machining. When you machine the repair to match the original surface the visible part of the fasteners will be removed leaving you with an almost invisible fastener. I understand what I am saying but I think my description is so poor that it may not be clear. Anyone who can improve my description is welcome to do so.

Cheers,

Nick

[parvum]

Hi All Thanks very much for your replies and  sorry for the late response.The beast is all in bits right now and not fit to be seen, there will be a delay while my finger heals, I let it get eaten by a door. The T slot damage is two cracks on each side of the slot running from the edge of the cross slide to about one inch in and about 1/4 inch from the edge of the slot on both sides.With the compound at a right angle to the slide the tee bolts are clear of the damage, but to cut a taper one of the tee bolts would be in the damaged area, although the metal does not seem to have shifted and the "bits" don't move under finger pressure,the cracks are visible running through the thickness of the top surface of the slide.Am I being too anal about this as tool pressure should be downwards on the bolt nearest my side of the cross slide but sods law, upwards on the damaged area,albeit covered to some extent by the compound base. Is it worth veeing and brazing these cracks or do I risk distorting a fragile casting.

Thanks again
 Paul

[Arbalist]

Have you looked at this page Paul.

http://www.lathes.co.uk/hobson/index.html

[bertie_bassett]

rather then trying to braze the casting would some sort of epoxy be worth a go? might be able to force some down inside the crack which should hold things together well. and if not then you've not done any real damage to the casting

[parvum]

Hi Arbalist
Thanks for the reply First place I looked! Its a mine of information but not a whole lot on this lathe,nice pictures which were useful but no real info like spindle thread, looks like ACME pronounced flat tops to threads 1 5/8 diameter but 8 TPI need to make back plates to convert my Myford stuff. The geared headstock has some goo  in it that was once lubricant, whats safe to use, EP90? or will that eat bronze bushes, the tailstock has been converted to self extraction and has some strange add on to the gib system but it seems to be OK. It has no motor fitted and I need to find out the motor pulley size to give the designed spindle speeds. Any info from other owners will be much appreciated.

regards paul

[parvum]

Hi Bertie Basset
 I wondered if the inevitable oil in the cracks would make an epoxy joint fail, as the cracks are still closed what would you suggest to degrease a these cracks in the casting or would a Locktite product like 603 be better?I certainly like the idea of a cold process that does not involve further brutality!

[vtsteam]

Parvum, maybe you'll get some ideas from the boring table I did here?

http://madmodder.net/index.php/topic,8900.25.html

[bertie_bassett]

Personally id try an ipa solvent first to get the worst off then id consider putting it in the dishwasher ( when shwmbo isn't around)
The heat from the dishwasher shouldn't cause any damage and the jets would hopefully cleaan the crack right out.
There may be a risk of the parts breaking off, but if thats the case, they would have failed in use anyway

[RussellT]

Back to your original question - will an ML7 cross slide fit?  Are there any Myford owners near you?  Replacement with an ML7 cross slide would be easier and a much more satisfactory long term solution.

If you've got it in bits you can take the bits to a Myford owner - no need to borrow bits.

I'm not a Myford owner - can anyone else help?

Russell

[parvum]

Hi vtsteam, Thanks for your link, it was a fascinating vid, but your skills are way in advance of mine, but thanks for taking the trouble to try and enlighten me.
Thank you both bertie basset and RusselT. I think I had better try the replacement route as this lathe seems to have been a Myford clone, I'm still at the parts swapping stage tapping loose threads and turning either too big or too small are about my limit right now, I usually butcher wood, hand held tooling allows for more leeway.
Thanks again to you all for the trouble you have taken.

regards Paul

[Fergus OMore]

Back to your original question - will an ML7 cross slide fit?  Are there any Myford owners near you?  Replacement with an ML7 cross slide would be easier and a much more satisfactory long term solution.

If you've got it in bits you can take the bits to a Myford owner - no need to borrow bits.

I'm not a Myford owner - can anyone else help?

Russell

Actually there are ( to my knowledge)- TWO ML7 cross-slides. One is the standard short one and the other is longer.
However, there are (at least) two more. One is on the Super7 and the other on the '10'
To confuse further there are TWO more. One is the fixed vertical slide one and the other one goes on the remaining pivotting slide
You clearer now?

Now this cracked ML7 tee slot thing is nothing new. Martin Cleeve- author of Screwcutting in the Lathe cracked his and if you look carefully at what is on the front cover his is NONE of the foregoing, it is a Myford Special and isn't cast iron. It is steel. However, he extended a slide and he mended his cracked one and he fabricated another.

I've lost count.-forgive me.

All that I would suggest is that you measure YOUR broken slide- width and let us know the length involved. I have a long ML7 top, A Super 7 one and a fixed 'funny' because it probably came from a Zyto but seems to have all the markings of one from a ML7.

PM me, if this makes a slight amount of help.
 

Norman

[mfletch]

 This is what one guy is doing with a blown out T slot just mill out and blot a peace in I know its not that easy but its a start

[Pete W.]

Hi there, Paul,

If I understand your situation and enquiry correctly, you need to know the dimensions of the cross-section of the ML7 saddle dovetail on which the cross-slide slides.  This includes width, depth and dovetail angle, plus the position of the feed-screw axis in relation to the dovetail cross section.  I guess you also seek to know the length of the cross-slide and its feed-screw?  Have I understood that correctly?

I have an ML7 to which I added the long cross-slide.  I have not disposed of the original cross-slide (nor do I intend to!) but I'm quite happy to measure it and post the dimensions here.

I also have one of the gizmos that Myford sold to enable the ML7 cross-slide to be used on their ML8 wood lathe.  That has the same dovetail as the ML7 saddle, I can also measure that too.   (It will be easier to measure than the actual lathe saddle.)

If the ML7 saddle dovetail is larger than the corresponding part of your Hobson, I anticipate that the ML7 cross-slide will only fit the Hobson if there's scope to use a thinner gib-strip (and if the feed-screw axis positions are compatible).

You wrote that you usually work in wood - what measuring tackle have you got to measure the Hobson parts?

I hope to get some workshop time tomorrow - watch this space! 

[parvum]

Hello Pete Thanks for your trouble, The slide on this lathe is as follows:
Length 8.45"
Width 3.50"
Depth 1.00"
Dovetail 0.375" deep
1.975" apart at the bottom of the dovetails
The centre line of the feed screw looks to be in line with bottom surface of the slide and in the middle of the slide. Please excuse the vague
measurements I am used to a steel tape or if pushed a steel rule!
The slide dimensions have been taken with a vernier. I would anticipate some fitting to be required as I understand Hobson  lathes were made as one offs to order and I bet that none are the same to within a few thou

Many thanks

Paul

[Fergus OMore]

I'm pretty certain that quoted dimensions are for a ML7 at 3 1/2" wide but mine is longer at over 10"
The configuration, if it is like the lathes.co one is ML7. However, the ML7 looks thinner and weaker!
Again, the feed screws are not even similar.

Frankly, I'd replace with fabricated steel( despite having one for a ML7( long))

Hope this helps

Cheers

Norman

[Pete W.]

Hi there, Paul,

I've measured my cross-slide bits & pieces, here are the results:



I have to say that I'm suspicious of the height of the male dovetail on the ML8 adaptor - it looks too small for the cross-slide to bear on the right places.

I haven't measured the position of the feed-screw, if you do fit an ML7 cross-slide, I assume you'd have to modify the front bracket to take your H7 feed-screw, wherever that is?

I haven't dimensioned the angle of the dovetail on the cross-slide - it's 60°, the same as the adaptor.

There seem to be a few ML7 cross-slides listed on eBay.

I hope this helps - if you need any further dimensions, please ask. 

[Fergus OMore]

Paul

You should have Martin Cleeve's 3 articles on his fabricated all steel slide in your post box
Cheers

Norman