Making tools to mend tools to make tools

Someone moaned about the amount of politics and calendars:-

I may have let slip (to the point of monotony) that I have been rebuilding an Ebay basket case Hardinge HLV for the last 18 months.

At the start of March I started to work on improving the removable, hardened dovetail way bed. Having removed the bed, I measured its thickness in a number of places. The micrometer showed that there was at least 3.7 thou of wear. At least, because the micrometer doesn't measure to the bottom of the roughness.

I could have sent the bed away to be reground. Trouble is that I'm cheap. That's why I didn't just wait for a lathe to turn up in better condition to start with...

I reasoned that I might be able to grind the bed on my £75 J&S 1400 grinder.

Because the bed is38" long and the table travel on the grinder is only 24", the bed had to be ground in two sections. I got a bit of a visible furrow at the point where the table stopped at the end of the cut in the middle of the bed, but even after the roughing cuts, the bed thickness is now even to within a couple of tenths outside of that narrow furrow, which the carriage will ignore. I had to remove 6 thou to get rid of all of the wear marks.

Ok. That did for the thickness of the bed. Now I can think about the dovetails. The dovetails have a 1/8" wide, unmachined, vertical section at the top. I assume that I can measure from that to the dovetail on the opposite side to get an indication of the wear.

While thinking of that, it was assumed that the way to grind the dovetails would be to make a sine table. The old 6"x12" Humphrey's electromagnetic chuck that I inherited off father could be pressed into use for that. A 15" long bit of 1 1/4" square bar was milled into angle iron on the Myford and hinge pins turned on the ends. A couple of lengths of 2" square were milled and ground into L shapes for the sides. Holes could be bored in these for the hinge pins before final grinding to get the height of the side at the exact level of the bottom of the hinge pin. Something like this:-

|-----------------------------------| | | | |---| | |-------|_______________________|___|_| | /-\ | |/-\| | \_/ |________________________\_/___ | | |______________________________________|

Boring the holes means that the boring head that I got some years ago needed an adapter to fit the Myford headstock mandrel. Did that, got a set of taps from RDG to finish the internal threads, having had problems with getting these right before.

In the meantime, the junction box on the mag chuck needs sorting.The screws holding it to the chuck have waled out heads and one of the screws holding the cover on was sheared off before I was born by the look of it. No problem. Bit of 3/8" silver steel for the cap head screws and 3/8" brass for the countersunk screws. drill out the busted screw and run a 5/32"BSW tap down all the holes to clean them up..

A jig had to be made to hold a tenths dial gauge at a variable, fixed height and slide along the bed, measuring the variations in width. Just a bit of sawing, milling, grinding, drilling, tapping and Loctiting. Job done.

The jig shows that the vertical bits at the top of the dovetails seem to be parallel within a tenth, but that the dovetails have a reasonably steady 12 thou slope compared to the vertical bit. Bugger. The jig needs modifying so that it can measure one dovetail against the opposite dovetail. If I make a push tool to fit the boring head, I can use it with the Myford dividing head to make a ball turning tool and make some ball ended pins to go on the jig to bear against the dovetails. Haven't got any 1/2" round HSS. Never mind, make a

3/8" to 1/2" adapter to hold the 3/8" HSS that I've got.

To cut off the bit of round HSS to the right length, I can use one of the thin cut off disks I got for the grinder. Bugger, the wheel arbours won't grip something that thin. Never mind. Slice off a bit of 95mm bar and turn up a spacer to fit the wheel arbour.

Now, What was it that I was trying to do...

Mark Rand RTFM

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Mark Rand
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I like a workshop challenge as much as the next bloke who spends his working bay in the white collar world of email and meetings and I don't want to sound defeatist but wouldn't just have been easier to give it to someone with a big enough surface grinder?

OK, I'll get my coat.......


Reply to
Charles Ping

Mark. This is just a thought and it maybe no good, but could you shape the grinding wheel to suit the dovetail. Then you can mount the bed flat on the surface grinder. Maybe the angle is too much to shape the wheel to? Anyway keep going and keep us informed, it is a good challenge, Regards Alan

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Ah..but then he wouldn't have that nice furrow 2/3 of the way along the bed...

Regards, Tony

Reply to
Tony Jeffree

Mark, In all honesty, I hadn't a clue about your Hardinge HLV but suggest that it is a flat bed. Last year, I had my second or third flat bed Myford reground locally on a Lumsden for =A330+ Vat. OK, this is not quite Myford works or so on but it is a solution to get a pretty decent top which may only need a few swirl marks removed.

Have you a guy with a big Lumsden?



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The flat bit's done apart from that cosmetically annoying furrow, that might get another couple of finish cuts. The 11" wide saddle won't notice a 3/16" wide, half thou deep furrow, but it might allow grit to get under the saddle.

The bit that all the current work is for is the dovetails. At the moment, I don't even know accurately what the wear is on them.

I think that the point that I was failing to get across was that one job leads to another. To the point that you end up having so much fun, you forget what the original task was :-)

Mark Rand RTFM

Reply to
Mark Rand

Havent you finished that little job yet?

IGMC Dave (Who didnt buy an HLV recently)

Reply to
dave sanderson


Don't wish to rub salt into the wounds, but a really immaculate looking HLV went on Ebay a week or so ago for 1000.00. Chucks and all the collets as well. As for regrinding, some jobs are just plain left to those with the right kit, much as we would like to (sometimes stubbornly) think we can do it all ourselves.

Was quite tempted about that HLV, but can't justify that much for something that won't get regularly used, or otherwise earn it's keep...


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I doubt that many failed to grasp that! I'll bet a lot have BTDT, with or without tee shirts!


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I for got to mention that, when milling the bracket for the sine-table-to-be, I finally got around to surface grinding the washers on the thrust bearings of the Myford vertical slide to fit with a tenth or so of pre-load When I bought it via John and Charles' website, it had e metric screw and dial. The imperial ones that I got from Myfords fouled by about 10 thou when fitted on the bracket. After two evenings of careful measuring, calculating and surface grinding, the vertical slide is as good as it can get without an anti-backlash nut on the leadscrew.

Moral of that bit is, If someone offers you a surface grinder for a scrap price, take it. They are very useful toys. Plus, yet another iteration of the tools to make tools saga :-)

Mark Rand RTFM

Reply to
Mark Rand

Oh that I had the space... as it is SWMBO has ruled that the machines under a tarp in the garden have to go before Im allowed any new toys....

Dave (who is idly looking for a small grinder - if only to save making one...)

Reply to
dave sanderson

Mark Hi, I admire your determination and totally agree that "one thing leads to another" and while interesting can lead to us "not clearing the swamp of aligators"

One question I must ask though is why do you need to measure the dovetail to dovetail surface distance? I can't get past thinking the important issue is to get them as parallel to the top and each other as possible when re-grinding and as parallel to the bed axis as you can. I can't remember if the HLV bed is located with dowel pins or not so that a little adjustment of the axis would be possible when setting up. Surely, for grinding you can set up from your new top surface and the small vertical surfaces once you have mapped the wear on each dovetail face from its' adjoining "unworn" vertical surface to ensure that you grind suficient off to cover the double grind setup? If I remember correctly (long time ago) the HLV has a two part bed under the headstock so wouldn't the short piece under the far left (from front) give you the unworn figures to work out the minimum grinding to remove all of the wear. Alternatively couldn't you grind the headstock part of the bed first to just clear all wear and that will surely be enough to clear any lesser wear on the tailstock end.

Another comment would be why you need to measure the dovetail angle to such accuracy? If the bed surfaces are worn then surely you will be grinding the saddle as well to match. As long as the angles you grind on the bed and saddle are exactly the same it shouldn't really matter if it is 59 or 61 degrees?? Couldn't you use a simple 60 deg (ish) fixture for both operations?

Mark, I'm not looking to start any deep discussion just looking to understand what it is that I've obviously missed when thinking about the geometry. I have a very old flat top dovetail bed lathe that I would like to restore in the future and would like to learn from your experience before I decide to start and mess it up.

Best regards


Reply to

On Mon, 21 Apr 2008 13:53:34 +0100, Mark Rand wrote: .

Nah, just mill them off square and turn them into Box ways. (ducks and runs..)


Reply to
Peter Neill

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