New Myford Topslide to J A Radford's design

[Chipswitheverything]

Way back in the early 1970's, the New Zealand model engineer Jack Radford published a design in Model Engineer mag for making an alternative top slide for the Myford Super 7. 
  His intention was to improve the overall rigidity of the t' slide, make it possible to set it to turn parallel without the need for adjustment each time it was put on the lathe, and to provide clearance to bring the tailstock near to the workpiece without clobbering the t'slide body and handle.  Usually one needs to turn the Myford t' slide at an angle when working with a tailstock centre, rather annoying...
   The usual Myford design is still needed for short tapers and for setting over when screwcutting, though.
  I had rather liked the look of the Radford design for years, but though Hemingway does castings and sundries, the price ( about £84 ) was putting me off. Also, Hemingway's arrangement is that one swaps the whole Myford feed screw, dial and nut assemblage every time the two top slides are swapped over, I didn't fancy having to muck about doing that, but the price of a new feedscrew and ancillaries from "Myford" is now getting on for £100 .
   From "somewhere" I had long had a nice slab of cast iron, 12" by 6" and planed to about an inch thick.  Looking at J R's drawings a while ago, I realised that I could get the two main chunks for the new top slide from this slab, and not need castings.
  A year + ago, on a stall at the Guildford show, I turned up in a rummage box a v. good condition Myford feedscrew and nut ( from a vertical slide ), and a Myford topslide type handle, which I bought for a tenner or so.  No dial of any kind, but now I had the basic ingredients...
  This project has been done at odd moments since last autumn, I'll split it into a few write-ups with photos of some of the machining procedures.
Here is the finished slide ( with homemade four way toolpost ), and the slab cutting.  With a new, Sandvik, coarse blade, it didn't take anything like as long as I had feared that it would.   I bored the hole for the radii on the components before slicing it through.    Dave
 

[Ridjobradi]

That's a great looking project. I am looking forward to future posts.

Sent from my SM-T330NU using Tapatalk

[Chipswitheverything]

Thanks for your comment, Ridgobradi.        Having sawn out the bits and gained some handy smaller bits of cast iron for the scrap box, I checked out the flatness of the already planed but rather rusty surfaces, and did a bit of scraping and filing, checking against the surface plate,  so that the items would not be distorted when clamped to the milling table.
  Bringing the two bits to basic outline and shape was just straightforward milling, with attention to keeping things square.  I used a simple fence located in a tee slot in some setting up ops.    The fence is just a length of mild steel bar with bolts with shallow heads, that can be tightened back to the other side of the slot with a thin spanner.
 Marking out was fairly minimal, but gives a visual check that all is where it should be.

Fourth photo shows the underside, recessed in the central area, and the slot for the tongue that will match the Myford tee slot being milled in.  Very important to get, or to keep,  this parallel with the subsequent dovetail machining.
 
I was lucky with this piece of cast iron, it machined nicely with no blowholes or chill spots.   Incidentally, the drawing as presented in Model Engineer has an error in a dimension on the lower , main base component.  From the c/l of the feed screw to the cut out of the base on the further side, ie. away from the operator, is given as 1 3/32",  it should be 1 5/32".   Hopefully the dwg. as supplied by Hemingway has made the correction, but be aware!     I drew the end elevation of both elements out at 2x full-size to make a check of the alignments, it was quite a useful exercise.        Dave

[Andy]

This looks very nice work, Dave.
I do wonder why it is not better to do away with the top slide altogether though?
Putting the top slide back on makes it less rigid I would guess, and as set at 90 degrees to carriage makes the function redundant?
 

[Chipswitheverything]

Hello Andy, thanks for your comment.     I saw it earlier on, and wondered if any other lathe users would care to take up your point about a fixed parallel slide and its utility, but as they have not....
  It is a fair point, because over the years various designs for very rigid fixed toolholders, multi or single tool,  have appeared in the magazines, and I suppose there must be some users of them.  But I can envisage such a cross slide mounted holder being rather difficult to use when doing a lot of routine lathe operations. And in fact, the usual top slide, for all its versatility,  does spend a lot of its existence sitting there set parallel to the lathe axis...

 Without a moveable top slide, putting known increments of axial direction cut on becomes a bit of a game, because you either have to use the engaged leadscrew and not very convenient leadscrew handwheel, or perhaps put a carriage stop on the bedways and set the increment as a gap.     ( Admittedly, a DRO on that axis could help here, but they are not that common on smaller lathes, I have no plans to fit one.)
  If one has to , say, turn a not too long shoulder to a set length, or chamber out a bore to accurate depth, it's so handy to just use the top slide and its index when set accurately parallel, and the same goes for putting a few thou of cut on when facing. Then there are ops like grooving to width between left and right faces, easy to keep track of width and cut on the top slide dial... Although the travel of this new top slide is comparable to the Myford one, getting on for two inches, I wouldn't generally use it for that sort of traverse, but for all the fiddling stuff as mentioned above, I would not be without it.  The rigidity of this slide and its mounting and the support it gives quite close to the tool tip, even with the tailstock support being used, certainly exceeds the Myford arrangement  -  though as said earlier, one needs that top slide for the other functions.
  More write up later!,    Dave
 

[Chipswitheverything]

With the milling of the dovetails and basic elements completed, it was time to get the sliding components working nicely.    In his article, Jack Radford mentions ,but without much elaboration, that he scraped the machined surfaces so that the downward forces were taken not just on the lower horizontal areas, but also on the narrower top faces of the upper part of the dovetail slide, so that the contact is thereby greater.  ( The Myford slide has a small gap between the top of the dovetail itself and the underside of the moving top slide ).
  I was dubious that I could achieve this contact on two levels of the slide, but there was no harm in giving it a go!  So I machined the slide so that it would , hopefully, contact that upper surface as well as the lower one ( ie., I made the height of both "male" and "female" dovetails the same...  )
  With a lot of rather tedious scraping, bluing and testing, I did eventually produce a fairly acceptable blue transfer on all the flat surfaces, so that there is a very solid metal to metal area taking the tool loading throughout the slide.
  The gib strip is fitted with about a thou of clearance, the slide was able to move almost without any rock without the gib screws.  The gib was dowelled in position before the gib screw holes were drilled and dimpled into the strip.

[JR72]

Hi David
You leave me with very little to add to my past comments on your exceptional engineering expertise and seeing your JAR`s topslide  at first hand my previous comments still apply. This is absolutely amazing the work of a real craftsman. Very well done. I hope the next project won`t be too far away as I (and I imagine most of the Forum) get a lot of pleasure in seeing anything you have made. The only thing that I don`t understand is that you only made one topslide knowing full well that I also own a Myford Super7.

Well done David always a pleasure to see your photos and write ups but most of all to actually see your work.

Best wishes
John

[Florian Eberhard]

Hi Dave

Nice work on that compound slide!
Now about the scraping: I think you are using a little too much bluing compound. That amount works for the beginning of work when you need to see pretty small high points but as you get flatter, you should reduce the amount of color used.
The scrapers you use will make the work really painful because they are too short. A good size is in about 50 cm (or 20 inches)  long.
Besides, the two bent scrapers wont be handy for scraping a flat surface. They are rather designed for scraping work on bearings like conical bushes that are fitted to a shaft (like a lathe main spindle bearing)

So if you intend to do some more scraping, i can only recommend to build a longer scraper (you could just solder a piece of carbide on the tip of some flat material and then grind it into shape and sharpen it)

Florian

[stvy]

Hi,

I really like this project. I just purchased a second hand  copy of the J A Radford's book and its nice to see one of the projects on the internet.  Thanks for posting. I'll be sure to read up on this project when I get the book.

I have a question or more of a discussion point if I may. What is the pros and cons of going with this fixed top slide rather than just simply a fixed tool post mounted directly on the cross slide turning the lathe in to a 2 axis machine? Cutting multi start threads is simplified with being able to adjust the compound but what apart from that?

Thanks,
Steve

[Chipswitheverything]

Hello guys, very appreciative of all your comments.   John, it was a pleasure to show you the slide in situ, now you're meant to rush home and start making one for yourself!   But Christmas is still a way off, if I have the odd hour to spare....

  Florian, you are right that I am not well equipped with a good scraper for such a task.  At the "Brooklands " Model Engineer Exh a year ago, a chap was demonstrating scraping and letting people have a go, and he had some excellent commercial scrapers of the size you are mentioning, and I could do with a tool more like that.  I look out for second hand tools, but such a scraper has not come my way.  Could be made at home, as you say.  The blue, yes, that sort of thins out as I successively wipe it away from the surfaces and make do with what is remaining on the plate....

  Steve, your query is pretty much what Andy was asking about a few comments above, which I did my best to give some ideas about on my Sept 1st comment.  I'd still be pleased to have some further remarks from other machinists, hopefully in support!!   Apart from anything else, the late Jack Radford, who was an immensely capable machinist and tool designer, was of the opinion that this alternative topslide was perhaps the most useful and satisfactory of all of the many ingenious accessories that he had made for his Myford lathe.  In his Model Engineer article he argues the points in favour of being able to use this alternative fixed topslide quite comprehensively.
  Dave

[Ye-Ole Steam Dude]

Beautiful piece of craftsmanship, thanks for sharing.

Thomas

[kvom]

Seems the compound can't be rotated.  Any issues with that restriction?

[steamer]

Hi Dave

Nice work on that compound slide!
Now about the scraping: I think you are using a little too much bluing compound. That amount works for the beginning of work when you need to see pretty small high points but as you get flatter, you should reduce the amount of color used.
The scrapers you use will make the work really painful because they are too short. A good size is in about 50 cm (or 20 inches)  long.
Besides, the two bent scrapers wont be handy for scraping a flat surface. They are rather designed for scraping work on bearings like conical bushes that are fitted to a shaft (like a lathe main spindle bearing)

So if you intend to do some more scraping, i can only recommend to build a longer scraper (you could just solder a piece of carbide on the tip of some flat material and then grind it into shape and sharpen it)

Florian

Anderson tube scraper  works wonderfully....you can get them new, but no need as you can find them used, or just make a copy.

[Stuart]

Seems the compound can't be rotated.  Any issues with that restriction?

One issue that stops me from making one is that I have the myford taper attachment , as a myford does not have a telescopic feed screw you need to use the top slide to put on the cut when using the said attachment .

[stvy]

Hello guys, very appreciative of all your comments.   John, it was a pleasure to show you the slide in situ, now you're meant to rush home and start making one for yourself!   But Christmas is still a way off, if I have the odd hour to spare....

  Florian, you are right that I am not well equipped with a good scraper for such a task.  At the "Brooklands " Model Engineer Exh a year ago, a chap was demonstrating scraping and letting people have a go, and he had some excellent commercial scrapers of the size you are mentioning, and I could do with a tool more like that.  I look out for second hand tools, but such a scraper has not come my way.  Could be made at home, as you say.  The blue, yes, that sort of thins out as I successively wipe it away from the surfaces and make do with what is remaining on the plate....

  Steve, your query is pretty much what Andy was asking about a few comments above, which I did my best to give some ideas about on my Sept 1st comment.  I'd still be pleased to have some further remarks from other machinists, hopefully in support!!   Apart from anything else, the late Jack Radford, who was an immensely capable machinist and tool designer, was of the opinion that this alternative topslide was perhaps the most useful and satisfactory of all of the many ingenious accessories that he had made for his Myford lathe.  In his Model Engineer article he argues the points in favour of being able to use this alternative fixed topslide quite comprehensively.
  Dave

J A Radford was certainly more knowledgeable than most and certainly me. So I dug out the book and read chapter 19. It was very interesting reading. I do not own a Myford lathe so I had not realised that a great many benefits are to be had with this design. As a boxford owner I was simply not aware.

I do have a soft spot for the special tooling designs he did, very interesting. It would be wonderful to see more examples. Is there any internet resource with colour photographs of any of his other designs known to anyone?

Thanks,
Steve