Holding work on the cross slide

[Robin GrahamParticipant @robingraham42208]

[Robin GrahamParticipant @robingraham42208]

I'm making something which wants a a spindle running between the two 'tines' of a fork. The distance between the tines is about 100mm. Obviously the seats for the bearings must be accurately lined up. I've read here and elsewhere that this can be done by mounting the work on the lathe cross slide and using a boring bar between centres. I've never done that, but to do so iwould be a jump up the learning curve for me. My problem is how to mount the work on the cross slide…

No T slots! Maybe I could mill a T-slot which as well as helping with this project would allow me to use a rear mounted tool post, which might be handy at some point . But would I risk knackering the machine by doing that? This is the meat I have to work with:

Any suggestions/opinions?

Happy solstice/ Xmas, to you all, Robin

[John HaineParticipant @johnhaine32865]

Strategically placed threaded holes.

[Ady1Participant @ady1]

Make a t-slot cross slide

It will open up a new world of opportunities by making your lathe far more flexible

A simpler approach would be to add another level which you could screw onto the existing arrangement

So you screw the t slots onto the existing cross slide

Edited By Ady1 on 21/12/2018 23:52:52

[ZanParticipant @zan]

Agreed drill and tap the x slide and fit anti swarf plugs, you don’t want dross falling into yjrpe slide internalsOr fit a 6 mm plate on top. Don’t make a new x slide, too much work for a single job at some point buy a miller

Do not cut slots in the slide at has been designed as a single solid unit and will weaken it.  A set of holes will give great versatility

Edited By Zan on 22/12/2018 00:28:28

[Chris TriceParticipant @christrice43267]

Machining slots into a relatively shallow cross slide casting like yours could seriously weaken it. Drilling and tapping holes in strategic positions is the best and least troublesome solution as John suggests.

[HopperParticipant @hopper]

How big is the job? Could it be clamped in the toolpost and bored through that way?

Might you also be able to hold the job in the four jaw chuck, or clamped to the faceplate, and bore through both holes in one setting with a conventional boring bar?

Edited By Hopper on 22/12/2018 01:34:22

[John ReeseParticipant @johnreese12848]

Most older lathes had t-slots in the wings of the saddle for just the purpose you described. It is unfortunate the new lathes were not so equipped.

You might consider a tapped hole in each wing of the saddle. Make two t-slotted bars to run front to back and bolt down to the tapped holes.

[Paul LousickParticipant @paullousick59116]

You already have T-slots for mounting something (circular type). I would not recommend drilling and tapping new holes into the cross slide

Make an adaptor plate that has a spigot to go in the existing hole and use the existing mounting studs to secure it to the cross slide. You can then do whatever you want with the new adaptor plate. Add tapped holes or T-slots and bolt a vice, angle plate or vertical milling slide to it. Even weld something to it without weakening the cross slide.

A catch 22 problen arises. You cannot do any milling on the lathe without some form of mounting arrangement, so a simpler, fabricated version may have to be made first so you can make a better version. A lot of work but it could be done.

.

[JasonBModerator @jasonb]

Why not just put some longer tee bolts into the existing toolpost ring, then all you need is a bar with two holes in it to go over the top to clamp down your work with suitable packing to raise it to height. Or use the two long studs with the usual style clamping plates and rear support. No drilling of the existing and not much in the way of additional work and you keep the max available room from ctr of lathe to cross slide.

Edited By JasonB on 22/12/2018 07:13:25

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Robin Graham on 21/12/2018 23:20:11:

My problem is how to mount the work on the cross slide…

Any suggestions/opinions?

.

Make a thick plate, or block … with tee-slots or tappings, to taste … and with two counterbored holes anywhere on the p.c.d. of those existing fixings.

Shorten, drill, and tap two cap-head screws to make a pair of sleeve nuts:

 No modification to, or further dismantling of, the lathe is required.

I did something similar, decades ago, and it worked fine.

MichaelG.

.

Edit: Credit to Paul, for the same concept

Edited By Michael Gilligan on 22/12/2018 08:30:03

[Michael GilliganParticipant @michaelgilligan61133]

Posted by JasonB on 22/12/2018 07:12:08:

Why not just put some longer tee bolts into the existing toolpost ring …

.

May risk breakout of the circular slot, if not appropriately backed-up with spacers

MichaelG.

[Mike PooleParticipant @mikepoole82104]

**LINK** A small table is available from various suppliers. Other items like an angle plate, vee blocks, vices etc. Can then be easily utilised.

Mike

[George JervisParticipant @georgejervis86082]

Hi Robin,
When I did my first basic Line boring on a lathe I managed to clamp a angle plate to the cross slide T slot and then clamp the work to the angle plate running a homemade boring bar between chuck and tail stock. Would this be an option for you? I did put a short clip on you tube

George (little John)

[John HinkleyParticipant @johnhinkley26699]

It is possible to mill tee slots in the existing cross slide – IF there's enough meat in it to do so without significantly weakening it. I wanted to mount, specifically, my ball-turning attachment to the cross slide and later some other items for line-boring etc. In my case, I initially purchased a secondhand Myford cross slide and intended to modify it to fit my Asian-made 9×20 lathe. You can follow my progress throuh my album "Cross slide modifications" should you so wish, but to summarise:

The original looked like this:

And, having abandoned the Myford route ( for reasons discussed in the album ), I machined slots transversely thus:

No doubt, there is some weakening of the structure of the cross slide, but so far – about four years – no sign of significant flexing etc. I make no guarantees that this will be suitable for your application, however and I made the modification knowing full well that it could all go horribly wrong – though I did make some carefully considered calculations (gambles!) along the way!

John

The slots, by the way, are smaller (and metric ) than Myford ones but I consider them to to adequate to withstand the likely stresses that will be imposed upon them by the sort of work to which I intend to put them.

[John PParticipant @johnp77052]

I had a similar problem with my Warco lathe .I made an add on plate the full length of the crosslide just over an inch thick ,it is held with six 6mm cap head bolts ,holes for mounting parts are drilled as needed.If your lathe is similar to mine about the rear third of the crosslide is little more than a cast in cover and is quite thin in section so careful placement of the bolts is required.

The topslide mounting ring will most likely be too far from the centre line of the machine to be of any use in holding work in any event to fit longer tee bolts you will probably have to remove the crosslide.

John

[Neil WyattModerator @neilwyatt]

Nervousness about cutting tinto the cross slide is probably misplaced.

The large circular cutout for the top-slide attachment doesn't appear to cause any problems with its rigidity.

I doubt any modification will involve the removal of anywhere near as much metal. This suggests that threaded holes, another cut out or even t-slots in the other end shouldn't cause problems, but don't go too close to the existing hole.

Bear in mind the much smaller top slide takes similar forces to the cross slide.

My mistake when making a t-slotted cross slide was to use slots that were far too big, as forces when milling or boring on the lathe tend to be much smaller (as cuts are more conservative) t-slots to suit M8 or even just M6 t-nuts should be ample.

Neil

[Clive FosterParticipant @clivefoster55965]

Neil

Don't know if there is, in practice, a significant reduction in cross slide rigidity from additional Tee slots but if the base of the slot is left too thin its certainly possible to encounter cracking and break-away issues at the junction between the base and the Tee slot upright. I have seen thin walls between more substantial scantlings and ribs that have apparently simply cracked by themselves at the junction without any undue or unnatural force involved. Cooling stresses could well be the case in systems left as cast but that's probably not the case for similar failures in sections machined from solid.

Seems to be general machine tool practice to avoid making Tee slot bases and upper bars significantly less than 1/4" thick unless unavoidable. Useful though they are the Myford ones are notoriously on the fragile side of things. Pretty much unavoidably so given the limited space available. The upper slide on my Clarkson tool grinder is 3/4" of an inch thick and carries a 1/4" tee slot right in the middle. Seems to support standard practice as it basically just "looks right".

Its probably pertinent to note that the cross-slide of my Smart & Brown 1024 is of similar thickness to that on Robins machine. It has a rectangular array of 6 1/4" tapped holes towards the rear which many be used to mount accessories. As far as I know the only factory fitment exploiting these holes is a rear tool post mounting plate and associated tool post. Seems to be no reason why Robin couldn't copy this arrangement to mount a Tee slot sub table. Probably a longer table also exploiting the topside mounting bolts would be the most secure way. Might need a bit of care to ensure that the slide isn't distorted should either or both of slide top face and Tee slotted sub-table not be properly flat. A thin layer of J-B weld or similar strong filler laid between the surfaces and left to go off before fixing together might be prudent precaution. Oil or grease on the cross-slide covered with cling film should suffice as a parting agent.

Clive.

.

[Neil WyattModerator @neilwyatt]

Fair points Clive, but assuming that in this case the cross slide has the same thickness of metal all along, modest t-slots are going to create lot less weakness than that blooming great circular t-slot.

Neil

[Robin GrahamParticipant @robingraham42208]

Thanks for replies. If there had been a 100% consensus that it was perfectly OK I might have taken a deep breath and gone ahead with milling slots, but as there isn't I won't. I can adopt one or other of the alternative strategies suggested – probably drilling/tapping a couple of holes and using the existing circular slot. I shall still regret not having a t-slotted slide though, just seems a Good Idea!

Thanks again, Robin.

[Clive FosterParticipant @clivefoster55965]

Robin

A versatile and effective solution to your work holding issue would be a "grid of tapped holes" plate of similar size to the top of the cross-slide. Front held down by the top slide studs and rear by cap screws in some strategically placed tapped holes in the cross-slide.

Half inch nominal thickness aluminium tooling plate would be a good choice of material but it is rather expensive and may take bit of finding in a suitable size. A square or five spot dice layout of 1/4" or 6 mm tapped holes on a repeating inch or 25 mm pattern gives plenty of scope for holding and is adequately strong. If more holes seems good 5 mm on a 20 mm square repeating pattern would work and still be plenty strong enough. For inspiration consider something along the lines of the Thor Labs Optical breadboards here **LINK** or **LINK** and **LINK** perhaps.

Adds up to a lot of holes to drill and tap though so maybe just buying one would make economic sense as there are a couple of about the right size in the second link. Part 1530/FM is 150 x 300 mm is £70 (ish) and 1545/M at 150 x 450 mm £100 (ish) pre tax, imperial equivalents at similar prices too. Un-anodised ones are cheaper but easier to damage and they don't do a cross slide size one but the two smaller ones at under £40 might be worth considering. Not cheap as chips but if you have to buy material and a nice new set of taps the extra cost to save considerable work isn't completely silly. Don't, whatever you do, just rough up a that'll do plate and fit a few holes for a specific job. Always far more trouble to go back and fit more the next time you use it. (I usually end up with a complete proper do-over so might as well have done it right in first place.) Half the time the holes carefully put in just the right place turn out to be in the wrong place when you get down to the job. How do I know.

Concerning bolt hole positions the cross slide on my Smart & Brown 1024 is probably of similar size to that on your machine so you could take inspiration from the accessory fixing hole positions provided. The flat, rectangular top area on my cross slide is 17 1/2" x 5 1/4", 445 mm x 133 mm. The six 1/4" threaded fixing holes are in a rectangular 2 rows of 3 across pattern 3 1/2" x 1 5/8", 89 mm x 41 mm, with the first row 3 1/4", 82 mm from the rear end. Nothing magic about those dimensions but it does illustrate what the professionals found satisfactory.

Clive.

[Chris Evans 6Participant @chrisevans6]

The cross slide on my 14" x 40" Taiwan lathe (Harrison M300 copy) was always the weak link in an otherwise good lathe. When I had finally had enough of the problems I made a new beefed up slide. An extra 12mm or so on thickness allowed tee slots to be cut and I have not missed the bit of height over the cross slide. A simple polystyrene pattern was used and simply burnt out at the foundry. I think the casting was around £30 for a cash sale. Having a Bridgeport mill simplifies the milling of the slide but it could be done on a smaller machine.

[Robin GrahamParticipant @robingraham42208]

Thanks Clive & Chris for further suggestions. I had been thinking along the lines of making an auxiliary plate – my local ME supplier does 1/2 inch ali plate at £16.90 / sq foot, the cross slide is roughly 13x 5 inches so under a tenner to make it myself. I was indeed planning a 'that'll do' solution, but shall heed Clive's advice and make a 'proper job' – I'm sure it'll pay off in the long run. The Thor offerings look nice, but I'm retired and have more time than cash.

I could (just about!) fit the work on my little mill if I were to go along the route of making a new slide, but it would be an ambitious project for me, particularly as it has a tapered gib – thought maybe the taper is only on the saddle, I'll look – something to bear in mind for the future, but I think an auxiliary plate will sort me for now.

Regards, Robin

[Clive FosterParticipant @clivefoster55965]

Robin

Excellent price for the alloy plate. Really shifts the "make or buy" needle when you can buy a nice piece just the right size. Obviously verify that its flat. Last piece in that size range I had was probably off an extruded bar and was pretty good but not flat-flat. Very glad that I had most of a millimetre machining allowance to play with which made getting it just so straightforward. Piece of tooling plate cut to that sort of size would probably be around £40! Lotta money to pay just to be sure its flat.

As you are doing proper job its probably worth making it so that it can also be used on the mill. With suitable clamps, more to make, a grid of holes plate can be a better for small or irregular parts than a vice or trying to clamp direct to the table with the usual fixing kit.

Put a Thor labs one on my first mill, a BCA, longer ago than I care to admit and was well pleased despite the not inconsiderable expense as they were much more expensive then.

Been saying a couple of times a year for about the last decade "If I get one more job like this I'm gonna make a grid of tapped holes plate for the Bridgeport. But it never quite happens.

Happy Christmas.

Clive.

[Author]

Posts