Need some advice on my HF 7x10 lathe

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ric686

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I've decided to dive into improving the operation of my 7x10 lathe and am learning a lot in the process. I worked on the cross slide some and was able to smooth out the operation of it, but turned up some things that I'm fairly sure aren't right about it. I hope you'll forgive my lack of knowledge because I am certainly a newb. I don't know all the nomenclature for the parts of the cross slide dovetail so I pointed out a few thing on the photo below.

My next project after the cross slide was going to be an attempt at tapered saddle gibs, but on the advice given on some of the pages about it, I started checking the accuracy of the saddle and ways before doing anything with the gibs. What I've found is that it appears that no two surfaces of the saddle are aligned. The cross slide dovetail on the saddle drops about .006'" from front to back measured from the ways and one side is about .003" lower than the other. The cross slide gib rubs on the lower dovetail flat on the saddle, but the cross slide itself doesn't even touch it.
Am I correct in thinking that the cross slide should be riding the smooth bottom surfaces of it's "feet" rather than the rough underside that's riding on the top of the dovetail on the saddle?
Should I try to level the saddle front to back by taking down the inside of the saddle front V groove or shimming the back flat?
The only other machine I have is a HF Mill/Drill. Should I even bother trying to correct the saddle dovetail surfaces with that or would I be better off just getting another saddle from LMS? I don't mind risking the one I've got for the sake of a useful learning experience since a replacement is available.
Is it even safe to assume that another one would be any better?
What is the proper nomenclature for the various dovetail surfaces? What about the surfaces on the bottom of the saddle that it rides on?
I get mixed messages on brass vs. steel vs. cast iron cross slide and compound gibs. Is one better than another?

Sorry for the pile of questions, but like I said, I'm a rookie and I want to make things better the right way rather than making everything worse.

Here's what I'm talking about:
7x10Saddle.jpg

Thanks to all for the helpful info I've read on this forum. It's nice to know that a newb like me can ask questions about the basics here and get helpful replies.

7x10Saddle.jpg
 
Hi ric686
follow Kevins good advice aldo you may look at my site ( see bottom of this page).or search 7X10---12--14 on this Forum.
The cross slide is not to touch the flat surface but lightly clamp on the V section, winding the screws in pushes the gib plate against the underside of the V and pulling it down on the top, giving a positive location that is free to slide.

If you need help just shout.
Brian
 
Thanks for the links. I know about most of them and I appreciate getting the ones new to me.

BRIAN said:
The cross slide is not to touch the flat surface but lightly clamp on the V section, winding the screws in pushes the gib plate against the underside of the V and pulling it down on the top, giving a positive location that is free to slide.
Click to expand...

Thanks Brian. I want to make sure I'm not mixing up terminology.
When you mention the V section, I assume you're talking about the two angled surfaces of the dovetail, not the V way under the saddle that rides on the front way of the bed, correct?
Just so I'm sure I understand, the roughly machined underside of the cross slide should ride on the top flat surface of the saddle dovetail that is above the angled surfaces of the dovetail? I was assuming that the two ground surfaces of the cross slide that are below it's angled surfaces should ride on the two surfaces below the saddle angles. That's the way I understood the explanation on this page http://www.mini-lathe.com/Lapping/mt_lap.htm on mini-lathe.com about lapping the compound slide. He says that the cross slide is done the same way, thus my confusion. Is there standard nomenclature for the various surfaces of a machine dovetail?

Thanks,
Ric
 
The proper terms escape me at the moment. It's in there some place, I just can't access it. Things like that happen when you get my age.The cross slide should not ride on the top of the saddle dovetail. My cross slide clears the top of the dovetail by 3/32 or so. If the lathe is under warranty, you may get the saddle or cross slide replaced. The saddle seems to me to be off, based on your stated measurements. That doesn't mean the cross slide couldn't be off too.

You might see if you can locate a sympathetic machinist with a big cast iron mill that could re-manufacture the dovetail. I would not trust a mini mill to do the job if there was any other way. If you are unlucky enough to have to go it alone, and the cost of having a commercial shop do the machining. I would suggest that you hog off the top of the saddle dovetail top to get the the clearance you need. Then hope like heck you can get the slide scraped in...

Larry
 
I would say relax a bit about the cross slide. It doesn't have that much effect on things as other parts in usage. Put it further down on the list. First thing though is you need a reference surface to check things against if you are going to get serious about it. If you are measuring the cross slide from the ways, are the ways parallel? How much variance is the ways and how much is the cross slide?

The tapered gibs. I have done them. Brian's mods also make a lot of sense. The only thing really different is that the tapered gibs don't require any permanent changes to the lathe. The tapered ones were fun to make though. I was pretty conservative on size and the gibs ended up being a bit thin. I am actually thinking of rebuilding mine to use straight gibs with set screws. They don't really wear that fast and the tapered ones are a bit flakey to make. As I got through the skin of the stock, they started curling. I should have stress relieved them first. Live and learn.

As far as material for the gibs, you will get a lot of varied advice. Everything wears. That is why they have adjusters. What rate is acceptable is a personal choice. I chose brass because it was easy to work with and available. Cast iron works well. You could also make a case for some of the plastics like the Sherlines use. These little lathes don't put out a lot of power to torque things around. I wouldn't be afraid to make some out of delrin.
 
There are a couple of dedicated books to the mini lathe in the Workshop Practice Series:
#43, The Mini-Lathe by David Fenner
#48, Mini-LatheTools & Projects, David Fenner.

Home Shop Machinist also has a series (started in 2013) Additions & Modifications to the Mini-Lathe:... by Ted Hansen. The series started with the Nov-Dec 2012 issue. Look at
Mar-Apr 2013 discussed Bed wipers & Carriage Ways & Sep-Oct 2013 Alignment Essentials.
 
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