[SPEEDRE]

A long time ago I bought a Grizzly Mini Lathe. It sat in the shop for some time before I used it. I am not a machinist, but, I know more than enough to get me in deep hot do-do. Well here are my issues. First I smoked the controls, bought the H.D. edition from Little Machine Shop. Then I decided to upgrade to the digital counters for the cross axis. They are not made right!. I have disassembled and reassembled this many time s trying to get it right. Both lead screws are too long so there is backlash in both. And the gibbs, well, that is an interesting story. I can get them almost perfect except, Once they pass the edge of the dove tail, it all gets way sloppy. If I re adjust its just, well, gets wonky to the extreme. I have thought of several fixes but, if I try to make a precise washer to take up the slop, without an accurate lathe how can I do it?. Do I purchase a different style gibb bar? Do I purchase a new cross slide assembly, or what?. I guess I want to ask how to make it right I need some input from people who know more about lathes So let's hear from you!

[TroyO]

Hmmm, others may have a better idea but maybe your gibs are bent (Or just never were flat to start with)?

I took mine out and flattened then using sandpaper glued to a granite tile.

This page shows the proceedure...

http://www.mini-lathe.com/Lapping/Lapping.htm

If the dovetails are OK, with a flat gib you should be able to adjust it so the play is about the same through the whole travel.

You mentioned adjusting it... there are 3 adjustment points, are you using all of them?

This page walks through adjusting gibs...
http://www.mini-lathe.com/Mini_lathe...tm#adjust_gibs

[SPEEDRE]

Yes I used all three, even measured the amount protruding from the side. One thing when I took out the gibb piece there are wire burrs around three drill tip dimples on it. I did not file them off for fear this would somehow damage them. They exist on both axis gibb stocks. Should I file them off and flatten? And another issue. The tool holder, the square block that holds the tool bits is too low to properly center. Is shimming under it a sound idea. I liked the lantern type from the old days.

[Stirlingbuilder]

Yes I used all three, even measured the amount protruding from the side. One thing when I took out the gibb piece there are wire burrs around three drill tip dimples on it. I did not file them off for fear this would somehow damage them. They exist on both axis gibb stocks. Should I file them off and flatten? And another issue. The tool holder, the square block that holds the tool bits is too low to properly center. Is shimming under it a sound idea. I liked the lantern type from the old days.

As far as tool height, I had to shim up the ones I got for my 8x12. The tool holders are 5/16 and I found out 1/2 is right for my lathe. In the mean time, I have some 3/8 square stock under the tools and that is nearly perfect to use these for a while. They cut fine with a good solid mounted shim/tool.

[SPEEDRE]

I really think I can eventually conquer the gibb issues, it's the lead screw mess I can't handle. Any ideas anyone??

[TroyO]

I'm not really sure about the leadscrew issue... how much slop do you have and are you sure it's where the leadscrew mounts and not where the leadscrew fits the nut? For the latter, you can check this page for getting rid of as much of it as you can.

http://www.mini-lathe.com/Mini_lathe....htm#xbacklash

If it's the leadscrew where it mounts, then you may have to chuck it up in the lathe and "trim" it just a bit for a perfect fit? I'd check with LMS before doing that, though.

All that being said, you'll never get rid of ALL of the backlash. To work around that, what you do is always take your readings in the same direction. In other words, make sure you are ALWAYS cranking IN when you read the measurement... that way the slop is taken up and the readings are consistent.

[SPEEDRE]

Thanks for all the advise and input. I have tried all of them and I'm still not completely satisfied with the result I may just put in mothballs until I have the resources to replace the whole caboozle.

[gmfoster]

A long time ago I bought a Grizzly Mini Lathe. It sat in the shop for some time before I used it. I am not a machinist, but, I know more than enough to get me in deep hot do-do. Well here are my issues. First I smoked the controls, bought the H.D. edition from Little Machine Shop. Then I decided to upgrade to the digital counters for the cross axis. They are not made right!. I have disassembled and reassembled this many time s trying to get it right. Both lead screws are too long so there is backlash in both. And the gibbs, well, that is an interesting story. I can get them almost perfect except, Once they pass the edge of the dove tail, it all gets way sloppy. If I re adjust its just, well, gets wonky to the extreme. I have thought of several fixes but, if I try to make a precise washer to take up the slop, without an accurate lathe how can I do it?. Do I purchase a different style gibb bar? Do I purchase a new cross slide assembly, or what?. I guess I want to ask how to make it right I need some input from people who know more about lathes So let's hear from you!

Well unless you are using cnc backlash is not a problem. In fact backlash is required for a leas screw to work. At best all you can do is minimise it. But I have around 10-15 thous on both my cross and compound and they don't have any effect on usage at all. Now if I had a lot of time I would spend the time to reduce it but I really don't know why.

My Clausing mill has close to 15 thousands on both the x and the Y and that has never been an issue at all.

I suspect you may have a problem with worrying your lathe to death instead if just using it.. That seems to be a very common thing and I almost fell into that trap...

Garry

[RotarySMP]

I put bearings in cross slide drive of my 7x12 back when it used to be manual. That reduces the sloppy thrust bushing set up.

The cross slide nut has two nuts and a set screw, so you can make it rock on the set screw to remove the backlash (but make it wear quicker).

Lapping the ways of the 7x seriously improves them. The machining is so rough from production, that they quickly wear in, and you have to constantly adjust them. Lapping them in speeds this up in a controlled way.

[RotarySMP]

deleted.

[SPEEDRE]

Rotary SMP you are right on about how rough they are from the mfg's. I wonder if the new models of the Syil and Seig are any better. With rising prices and larger capacity machines it leaves one to wonder. Thanks guys

[BobWarfield]

Speedre, I hope you don't mind my saying, but you should try to make some things. These inexpensive tools will never be perfect, but they're capable of a lot more than most people would think. It's really hard until you start to build some experience to know what to do or how to do it to make them better anyway.

So give some work a try rather than just returning the lathe to the scrapbin. You may decide it isn't so bad, or you may decide you don't like machine work so much either. Even with a very rough machine, it's possible to achieve pretty amazing levels of accuracy once you develop your skills.

There's an entertaining thread about the much-maligned round column mills over on the HSM board that pretty much tells that story.

Cheers,

BW

[M250cnc]

Speedre I second Bob's opinion.

At the beginning of the industrial revolution there were no machining centres ball screws etc.

Mainly hand tools and machines made from wood.

When i finished my apprenticeship calculators hadn't even been invented yet.

You can't just buy some machines and then become an engineer, it takes years of experience.

Even though i have that experience i still took three attempts to get a pretty near perfect quill arrangement on my round column mill (FR31)

The design is more important than the the making, because no matter how good the machining if the design is wrong it will not work.

BOB where is this thread about round column mill's ?

Chin Up
Phil

[BobWarfield]

Phil, the round column discussion is here:

http://bbs.homeshopmachinist.net/showthread.php?t=37678

Cheers,

BW

[MrWild]

Thanks for the read. It amazes me how some can figure out a way to do things that make others slap their heads and go DOHhh. The re-zeroing of a round column mill is one such thing. Drill and ream a block you can bolt to a corner of your table. make the reamed hole a slip fit. !/2" is good enough, you can even do a .376" hole if .5" is too big. Toss a jig dowel in your quill and locate over your reamed hole set at you table 0,0. steel dowels have rounded ends or leads that will guide the dowel into place with light down pressure on the quill handle. A little jiggling on the X/Y handles has you zeroed in and ready to go in no time. Using a DTI will show you are within .0005". Sure, you will have to have your secondary work 0,0 so many inches from your table zero, but not a heart rending issue. Darn near painless.