Lathe compound slide vs surface plate

Cadillac
I was in the same place as yourself so I used some mild steel to make a straight edge for the dovetail. It was well worth the effort as rigidity shot way up.
If your machine isn't out very far, you can use the same gibb though you may have to put some shim behind it. I found that many factory gibbs are poorly fit. Getting the gibbs to fit right seems much harder than scraping dovetails to me.
The only down side is that steel is a pita to scrape.
Each step, each surface compleated can make a notable difference.
 
The gibb had a slight bow in it show in one of the previous pictures. I was abl to get it straight by tapping it slightly with a piece of copper buffer and a hammer. I suspect it will move during scraping. I just got a nice donor piece of cast from a part from work that should work good for a dovetail straight edge. I need to cut it out of the part but I'm hopeful it's a good donor the part had extensive machining on it and finishes were good. Will see?
I figured I was putting this time into the compound why not check the cross slide? It's also been bugging me that my lock hole for the cross slide is covered by the dro scale. I have a way to use the lock with some mods but needed to take the cross slide off so that settled that off it came. Kind of disappointing but expected it almost after seeing the compound. Two high spots on opposing corners about .0006 all four corners blued but i was pushing and rockin. I find its really hard to pick a surface to measure from? Nothing is flat every surface has some sort of hollow tap, rock, or bow.
The one thing I'm really not liking is the gib for the cross slide! Bent banana in both directions, slide side not scraped ground on both sides, top and bottom look to have been done on a shaper. Gib is smiling in the vertical sense which explains why when adjusting the gib it would want to raise out of the dovetail. Ive done alittle of the flat sliding surface of the top slide. Idk about the gib having bows in both directions might be out of adjustment by the time I get it fitted and have read that shimming is not a long term fix more of a band aid. So I might take a stab at trying to make a new one I haven't tried getting replacement parts I suspect it being a hassle unless I can find a comparable part from a grizzly model or something idk haven't tried. I think I have the equipment to do the gib it just the talent I'm questioning. Well got some work ahead of me but I think it should pay for itself in the long run here's some pics. Last pic is where I've gotten with the bottom. Once the end got takin down the one side came right in the other side isn't far behind.
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tertiaryjim said:
Cadillac
I was in the same place as yourself so I used some mild steel to make a straight edge for the dovetail. It was well worth the effort as rigidity shot way up.
If your machine isn't out very far, you can use the same gibb though you may have to put some shim behind it. I found that many factory gibbs are poorly fit. Getting the gibbs to fit right seems much harder than scraping dovetails to me.
The only down side is that steel is a pita to scrape.
Each step, each surface compleated can make a notable difference.
Click to expand...
Mild steel moves too much, you want cast iron and heat cycle it on a grill then ring it, ring it like a bell by hitting it with a hammer to get the grain to stabilize.
 
Steel was all I had at that time and it was such a small straight edge for the compound that warp was not a problem. That was my first effort at scraping.
The ways were so far out that that even a poor quality straight edge could make a huge difference in rigidity. I purchased a cast iron bar to make a longer straight edge for the cross slide and other projects.
 
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