Building a crosslide

[8ntsane]

Hey Guys

Ive been away for some time now, dealing with medical problems.
But Im doing pretty good now, and have a project in mind for my lathe.

I have been thinking of building a new crosslide, as mine is pretty beat up over the
70 plus yrs of use. Id like to do one thats alittle longer, with the T slots for mounting back side tools.
The first thing that comes to mind, is there any outfits that make up rough castings to save me from machinig this totally from scratch? The next question is regarding the gibs. Mine has a taperd gib now, and looking at the gib, I would rather not try to reproduce it. Looking at it, appears to have too much possibility for error.

This brings up a question about the non tapered gibs. Ive seen lots of machines with them, and while they look to be abit more involved to ajust, they appear much easyer to make. The only thing Im not crazy about is the row of screws and lock nuts, but hey, I can live with that.

If you were building a new crosslide, would you use straight, or tapered gib, and why?

If you were building a new crosslide , would you use cast iron as original, or change to something else, and if other than cast iron,why?

Thx
Paul

 

[8ntsane]

Welcome back Paul.

I would build it with the tapered gibs. They are so much easier to adjust. I would probably buy the gibs rather than try to make them. I'm sure you could get some from Grizzly and then make the cross slide to fit the gibs.

As far as what material to use, I would probably go with cast iron. I can't give you a good design reason to use cast iron other than maybe it's less likely to warp when it's milled then CRS is.

Ed

Thanks Ed

I never thought of buying one, and making it fit. Just by looking at the original, those gibs might drive me insane trying to copy it. Work holding the gib would be a bit of a challenge I would think.

Im leahing towards cast iron, Only because it machines easy compared to steele.
I just hate cutting Cast iron, its such a gritty material. But, any machining would be done on well covered machines.

What is that company the south bend guys get those castings from? does anyone know? I think its ML somthing or other, never really paid much attention to it.

Paul

 

[pdentrem]

I would not likely use cast iron as it is tough to get a good finish for the running surface. I would look for cast steel instead. I would not worry about warping in CRS either. If the piece was not flame cut there will not be much stresses and if you are really worried about it, just toss it in the oven after roughing it out and let it sit there at 500F for couple hours. Works for me, yes it is not the NORMAL stress relief temperature but it works. If you do it on the 24th you can kill two birds with one stove!

 

[4GSR]

I've made several replacement cross slide tops and some with new gibs. Most of them built I used the old gib and allowed room for rescraping and fitting of the old gib. That way you didn't have to make new gib. Remachine the gib to get it straight first.
I have remachined new/old gibs. Yes, they are sometimes hard to hold. Just drill and tap small holes such as 6-32 or 8-32, with the holes spaced out to keep it from chattering from milling. Mount to a flat plate and secure to the mill vise or table. The flat plate it is secured to can be tilted in the vise to the desired taper. Use a 1" travel indicator to indicate in the correct taper in a given distance like 6" or 10" or whatever. Once that is done you can machine the taper.
To get the dovetail angle, tilt your mill head or use a dovetail cutter and cut. Take lite cuts to minumize warpage. Straighten by the peening method.

 

[george wilson]

How can you mill a dovetail by just tilting the head???? Unless you just refer to machining the gib,you must use a dovetail cutter. Otherwise,the square end of your cutter will dig a trench you don't want.

To make a cross slide with a tapered gib,the following method would work: Mill one side of the cross slide dovetail at an angle to begin the place where the tapered gib will go. Mill a dovetail to match on one edge of your blank gib material. I think soft soldering the blank gib to the angled dovetail would work just fine. The gib can be wide enough at this stage that you can get clamps on it to hold it down while you mill one side to the dovetail shape. Later,you will mill its other side and make it marrow ended as is usual.I made MANY steel segmented spinning chucks by soldering the segments together,turning them,melting the solder apart and wiping clean while hot(so the solder is liquid.) Solder your gib blank in place,then mill the other side of the cross slide dovetail parallel to the outside of your cross slide body. Then,without shifting anything,mill the inside of the gib parallel to the plain side with your dovetail cutter. Then,heat up the slide and wipe the solder off clean,using abrasive if necessary to remove the last traces-THOUGH,if there is a minute,EVEN(not lumpy) plating of solder left,I don't see how it would hurt anything since the gib doesn't slide-you just adjust it and leave it.

You will end up with a perfectly even dovetail slide with a tapered gib by doing this. You should also counterbore and drill and thread the hole,etc. for the gib adjustment screw at one end,of course. Make sure the slot you make in the gib,which the head of the adjustment screw rides in,has no extra play between its width and the thickness of the adjustment screw. If there is much AT ALL,when you screw the cross slide in the opposite direction,the gib will shift and make the cross slide too tight or too loose in one direction.

I recommend using cast iron for everything if you want a slide that will not wear for a long time. The graphite content makes it wear resistant,which is why cast iron is used in machinery with sliding surfaces.

 

[george wilson]

Cast iron is supposed to be machined dry,as is brass. You don't want that dust carried back around again and again by oil.

 

[pdentrem]

I do not take it personally but I never had any success on getting a good finish on cast iron without lapping. It always comes out looking and feeling grainy. Must be bad methods. I know it can be done but I gave up long ago on cast iron. Maybe better equipment will help. The Atlas lathe that I used to have would cut iron but the finish was no good. Cuts real easy but dirty that is for sure.

 

[12bolts]

Re machining Cast Iron.
We were told that it was self lubricating due to its graphite content and should NEVER be machined with lubricants.
Not being assertive. Just what we learned.
Like George W says, some materials are supposed to be machined dry....

Cheers Phil

 

[Highpower]

From Machinery's Handbook:

Cast Iron: Ordinarily, cast iron is machined dry. Some increase in tool life can be
obtained or a faster cutting speed can be used with a chemical cutting fluid or a soluble oil
mixed to consistency of 1 part oil and 20 to 40 parts water. A soluble oil is sometimes used
to reduce the amount of dust around the machine.

 

[DMS]

I will second (third) the use of CI. It has much better bearing properties than mild steel, so unless you want to fit brass/CI plates to the dovetails, or coat them with turcite or moglice, stick with CI. I made a dovetail slide a couple months ago for a T&C grinder I am working on. Used mild steel plate with a brass gib. It works alright, but it feels "sticky". Not that it is binding, more like pushing a piece of plastic through bubble gum. I used the steel because I had it, but I wish I had just purchased a chuck of pre-cast iron bar.

As far as holding the gib for cutting. I used a straight gib on mine, and held it to a block of steel using melted flake shellac. Take light cuts, and it works great. You could also use superglue. Heat with a torch to release.

DMS