What do these specs mean? Gauge plate.

[John Hill]

So many of my projects are stalled because I have no way to mount 'accesories' on the lathe cross slide so the plan is to fix an accessory plate on the top of the slide, just a slab of metal with lots of tapped holes ('cause I cant make "T" slots).

Nothing on the junk pile so I will have to buy,  is 'gauge steel' the stuff to use?  The specs dont mean much to me..http://www.easysteel.co.nz/site/story_images/Special%20Steels_Gauge%20Plate9080208162650.pdf

 It will have parallel, flat faces but can I easily drill and tap it?  Can I cut it (saw) if necessary?  Will a file just bounce off it?   (Like I said, the figures mean nothing to me  )  Though I assume it will look nice! 

Thanks

[Bernd]

John,

From what I read on that link it looks like that matel can be hardened. Meaning it's probably not to soft to begin with. A bright mild steel would work better for what you want. Don't know if they have something on the order of 1018 which is a very soft steel here in the US.

Not much help I know, but I'm sure you don't want to use gauge plate. Sounds costly too!

Regards,
Bernd

[bogstandard]

John,

You would do just as well using cold rolled plate.

Gauge plate, although very finely ground, can soon end up like a banana if you don't machine it up correctly. It has a lot of internal stresses in it from the initial manufacturing process. It is also rather tough to cut, Ralph can attest to that when I said he could have a lump of 1" thick gauge plate, but he had to cut it off the large piece I gave him.
It is really designed for making accurate jigs and fixtures that are machined, then hardened, finally being ground to size and shape required. Also it is very expensive compared to normal steels.

I showed you my plate that bolts to the original topslide fitting. That is 1/2" ali plate, and to me is plenty strong enough for the jobs I envision for it.

Bogs

Each post I am doing tonight , Bernd is just in front of me, so I might be repeating some of what he is saying.

[Darren]

You would do just as well using cold rolled plate.

I think John means don't use cold rolled plate, well I think he does......cos I couldn't even drill a piece I have.....

[John Hill]

Oh dear!  This is so difficult I think I will be going to play with my Lego!

Yea. Gauge plate would be expensive but I assume I can buy just as much as I need on the other hand I could go down to a couple of 'engineer' shops and someone might give me a slab of 12mm mild but it will have rusty surfaces and likely chopped off on a big shear so not really the size I need and curled like one or Mr Pringles potato chips, so then I would have to seek out someone who could mill/plane/grind it flat.

I was thinking the gauge plate would be one payment and one shop to get something immediately useable.

Bernd, I will see if I can find anyone who knows about 1018, maybe it is known by the same name around here.
[Later: I found it, we call it 'Bright commercial flat']


John, ali is not out of the question, at least I know I can drill and cut it but wont it have to be thicker than steel to get secure bolt fixings?

[Bernd]

Bogs

Each post I am doing tonight , Bernd is just in front of me, so I might be repeating some of what he is saying.

Sorry John. I'll slow down and let you ahead of me. You explained it much better than I did though.

Bernd

[bogstandard]

No, I do mean use cold rolled, I never have problems machining it.

Have you priced up the size of gauge plate you require John? It usually comes from the manufacturer in standard sizes, so it isn't a matter of just getting a piece from somewhere. It is usually megabucks per piece over a certain thickness, and maybe be prepared to pay for it by the square centimetre or inch.

If the metal supplier is any good, he should be able to bandsaw a piece of normal steel sheet for you, that way there should be no deformation.

Remember John, you are adding to the height of the cross slide by using a piece of plate on the top, so I would recommend going no thicker than 1/2", otherwise you might run into clearance, height and centre problems. It is sometimes a bit tight with nothing on there.

As long as you are not a gorilla with four foot arms, using spanners with 3ft handles, I shouldn't see you having problems getting well cut threads to hold in 1/2" thick ali. As long as you spead the load correctly with washers or shouldered bolts, with no side loading.

Bogs

Don't worry Bernd, it is better if we both confirm the same thing.

[Darren]

Sorry John,

I saw some British humour there that wasn't 

[John Hill]

As long as you are not a gorilla with four foot arms, using spanners with 3ft handles, I shouldn't see you having problems getting well cut threads to hold in 1/2" thick ali. As long as you spead the load correctly with washers or shouldered bolts, with no side loading.

Bogs

Dont worry Bogs, if I cut these spanners down a bit I should be right then!

[Actually, I was thinking of not running the tap right through so as to avoid the clamp bolt lifting the plate, distorting it and no doubt making mungery marks on my nice new lathe!]

[usn ret]

John,  I see a lot of info being kicked about but some additional info is needed ie, dimensions of the plate in its application, specifically length, width and thickness.  How are you going to attach the plate to the cross slide?   If we dig far enough into the specs "collectively" we can point you in the right direction.  OK??????

Cliff

[John Hill]

Cliff, the available space on the top of the cross slide is 120mm x 210mm and there is a maximum thickness of 13mm before interfering with the swing of the compound.  A plate of that size could be left in place which would be most convenient for day to day use.

If I decide that removing the compound when fitting and using the plate is not too inconveninet I could make the plate much longer, 120mmx 350mm and there would be no limit on the thickness.

The short plate I would fix semi-permanently by countersunk set screws into the top of the cross slide, for the long plate I could use the compound fixing bolts at one end and a couple of screws at the other.

The short plate would impose many limitations on what could be mounted due to the very reduced forward space available with the compound still mounted.

Whatever I use I think it needs to have a reliably true top surface and not subject to distortion through the use of clamping bolts etc.