# Getting started with tapered gib conversion on mini-lathe.



## David Kirtley (Mar 24, 2013)

Well, I decided a while back to start with putting tapered gibs on my lathe. The stock gibs are a pain to adjust and if I don't have them tight, they back out when I am making heavy cuts.

I started out with some mystery meat steel I picked up and some brass for the gibs. Well, this steel sucked. It was like machining very hard bubble gum.




Back to the drawing board.  I got out some new stock from my stash and it was much nicer. 




I laid out the features after pulling off one of the gib strips from the lathe and marking out the hole locations.




Next up was a taper. I was going to use my digital protractor but the batteries were dead. Well, it is not a critical angle and it doesn't really matter as long as they all match. Then I cut the tapers in the gib holders.




Next I cut the gib strips to width. 



No, those gib strips didn't magically get longer, I made some new ones. The originals I realized were not long enough to leave some meat for the adjusters. 

Next up, I need to stop by the store and pick up some superglue to temporarily fix the gib strips to the holders to mill the taper in them. Then all I have left to do is to drill the mounting holes, put on the adjusters and cut to length. Well, that and cut the clearance for the gear on the apron. I will try to get that done this next week as time permits.


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## David Kirtley (Mar 24, 2013)

Gibs tapered. Just a little file work and then add the adjusters and the clearance for the apron gear. I have them about 3/4 in long. I am trying to decide whether to leave it or not. Having it long will put the adjusters out easier to access. The downside is that they will be out easier to hit things with. I might have to drill the hole for the adjuster on the lathe. Not much room on the mill with them on end. I will probably just stick them in a tool holder and chuck up a drill bit.


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## David Kirtley (Mar 24, 2013)

For those that are on the fence about doing a tapered gib conversion, do not hesitate. I have one side (the back side) fitted and my lathe is more rigid and the carriage moves better than it ever has. I don't even have an adjuster screw on it yet. Just put in hand tight it outperforms the stock configuration. I need to slim down the taper a bit. I didn't really know how far it would set in place and I had to just guess. I was a bit too conservative.  I may wait a bit before I make the adjuster screw as it will likely wear in a bit and I want to have it with the most travel so I can go longer before I need to replace the gibs. Of course I am just guessing as I have no idea how long they will wear.


Drilling and tapping with the holder in a tool holder on the tool post went really well. I did finally use my hand crank for the spindle. Made tapping really easy. Probably would have been a bit nicer had I swapped out the collet holder for the 3 jaw but it held the tap "well enough".

UPDATE:

Well, I went ahead and got the front one on as well. Works really well. I still need to get an adjuster put on. Might make it. As it is, with them free in the holders, it is better than it was. I can hardly wait to see what it is like with them adjusted closely. I don't know if I will get new pics up. There really isn't anything to see. It looks like it did before except with a piece of brass sticking out the back. Once they get worn in a bit, I will cut the gibs to length and notch them for an adjuster screw.


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## David Kirtley (Mar 25, 2013)

Well, I lied. I guess there is more stuff to see.  Spent the evening making the adjusters for the gib strips. Did some tests in brass and then turned them for real in 1018 steel. The hardest part was the M4-.70 screw thread. Not the threading it, I just used a die. The problem was getting it a consistent diameter. Having a piece that thin and that long, it would flex too much. I just went ahead and turned it shorter so there was not as much to flex. I turned about 0.5 in to diameter, then moved in and did another half inch and so forth until I got to final length.

I didn't make a slot in the end for a screwdriver to turn them. I might put one later but I don't think I will need it. The knurled end should be enough to turn them by hand. They don't have to be that tight. There is a lot of leverage putting in the taper of the gib with the fine thread of the adjuster.  I can put the gibs in tight enough that the carriage can't move by pressing in with my finger.

All that is left is cutting the gibs to length and notching them for the adjuster. Maybe tomorrow.


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## David Kirtley (Mar 26, 2013)

Last installment.  I have them all installed. I am going to have to tear down and get everything cleaned and adjusted now. So far it feels pretty good except a bit of play since I took things out and put them back in to fit the adjusters. I think it will wear in ok though. I tightened them too much and my gib on the lead nut jumped loose. I got it taken down and looked it over but it is too late tonight to get stuff adjusted again. I had things adjusted really nicely but I had to get them loose (leadscrew and apron) to get the gibs in and out.


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## mikey (Mar 26, 2013)

Looks like that knurler is coming in real handy there, Dave! Nice job!


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## David Kirtley (Mar 26, 2013)

Thanks Mikey.  Actually I am getting the urge to make some more of them. I have extra knurls in two other sizes that came with the set and I really don't see a point in dealing with snap rings and stuff to swap them out.  This whole project has had me really thankful that I had picked up some extra tooling that has made it much easier. The only thing I really want now is to get some decent tap handles. The ones I have are awful.


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## mikey (Mar 26, 2013)

Speaking of extra knurls, do you have a straight knurl? If so, then you can make "square" knurls like this:




Basically, you take a straight knurl and measure the distance from crest to crest. Then use a sharp 60 degree cutter to space circumferential cuts that exact same distance apart along the knurl. It produces a nice square pattern. The idea is from George Thomas and it works rather well. My knurl is too fine and I need to buy a coarser pattern but this will give you the idea. I sort of like it myself.

Mikey


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## Chucketn (Mar 26, 2013)

David,
What plans did you use for the gibs? Please update this thread once in a while as you wear them in.

Nice build thread.

Chuck


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## David Kirtley (Mar 26, 2013)

chucketn said:


> David,
> What plans did you use for the gibs? Please update this thread once in a while as you wear them in.
> 
> Nice build thread.
> ...



I guess you could kind of say I followed Rick Kruger's plans but I really didn't follow them (or his instructions) except in spirit.  I kind of ramble when I was writing the posts so here is my version to compare with his. It is much simpler than it sounds. The only critical dimensions are the size of the holders, the position of the mounting holes, and the width of the gib strips:



 Get some material for the holders, 3/4" x 1/2". I started 4" long or so.
 Take one original saddle retainer and transfer the holes for the clamping screws.
 Mark off 0.3" wide for the tapered part opposite the holes (remember they are mirror images).
 Use an angled parallel (I made one a couple of degrees or so) and mill the taper section in the bracket to about 0.25" at the deep end  (because I was using 0.25" x 0.30" brass). Make the second one with the taper the opposite way (mirror image).
 Superglue the brass flat into the tapered section leaving a couple inches hanging off both ends and mill off the top of the brass flat level with the top of the holders in level in the vise (It makes the complimentary angle). I touched up on my belt sander.
 Knock the gibs loose (well, I didn't have any solvent for glue handy.)
 Straighten out the gibs from any warping or damage from whacking.
 Drill and tap for adjusters and make adjuster screws to fit.
 Trim gib strips by measuring where they fit in position leaving room for adjustment and notch for adjuster.
 Notch the front gib bracket 0.25 or so deep and 0.75 or so wide for clearing the gear on the apron.

Now, since I was just guessing on some of it, I actually should have left the gibs a little thinner. No big deal. I can make new gib strips later. All the angles and such are already set by the holders. The gibs are consumables anyway.  I should have just used delrin or UHMW-PE. The gibs only hold the saddle down to the bed. It is still metal against metal for the saddle. The back side doesn't have much force on it. It just has to counter the force of the cutter lifting the back of the saddle and it is far enough away for the leverage to be in your favor. The motor is only 350 watts. I could probably hold it down with my hand if I had to.

Other than the fun of making the tapers, it would be just as good and a lot faster and easier to just mill the slot level with no taper and put flat gibs and drill for several set screws to push the gib into the bottom of the bed. I have an extra bed and spindle and will go that way when I build that one up.


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## Sk8ter (May 3, 2013)

I seen this thread and would like to make a comment about brass...

brass is not a bearing material it will gall...bronze, cast iron, Are bearing materials

not trying to hurt feelings here but IMO this will not work very well for very long..


Lawrence


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## Richard King (May 3, 2013)

In my opinion the brass will work as it is harder then Turcite I have seen several machines built using brass gibs.  I hope the gibs were fit by scraping and new oil groves were machined in them.  I recommend a diagonal line versus a straight line groove.  I would also think you need to think about installing way wipers on all your ways and gibs.  If any of you care to learn about scraping check out my forum.  If the factory had installed the wearstrips that you removed, it looks like a very poor job, who ever did it.  We are discussing Rulon and tapered gibs in our forum now.

Many times you get scoured ways because the machine did not get proper lubrication and the way wipers failed and let the dirt and chips under the ways.    Rich


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## Sk8ter (May 3, 2013)

Richard King said:


> In my opinion the brass will work as it is harder then Turcite I have seen several machines built using brass gibs.  I hope the gibs were fit by scraping and new oil groves were machined in them.  I recommend a diagonal line versus a straight line groove.  I would also think you need to think about installing way wipers on all your ways and gibs.  If any of you care to learn about scraping check out my forum.  If the factory had installed the wearstrips that you removed, it looks like a very poor job, who ever did it.  We are discussing Rulon and tapered gibs in our forum now.
> 
> Many times you get scoured ways because the machine did not get proper lubrication and the way wipers failed and let the dirt and chips under the ways.    Rich



Hello Richard for someone who seems to be intelligent ...your not thinking clearly here......I repeat brass is not a bearing/sliding material it will gall against metal/cast iron etc.....this is a fact!!!.....dont believe me!!! look it up in your metallurgy book

why would anyone use something that is not as good or even as good as cast iron .....

cast iron has been used for bearing material for over 100 years!

Hell lignum vitae is a wood that would be suited for this job!


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## Sk8ter (May 3, 2013)

I just want to apologize to the OP...Like i said in my first post not meant to hurt feelings but facts are facts 



Lawrence


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## Richard King (May 3, 2013)

David,

I just emailed Dave Kruger to come and comment on this issue with the gib.  I see Dave wrote his Instructions in 2001 on how to convert to taper gibs and he recommend using brass.  I also see Rick is an expert on the Mini-Mill Forum.  I think his opinion here would be of value and how the brass gibs he made back in 2001 are doing.  Here is a link to the info you also provided to the group.   I think you did a bang up job on the gib and love the knurled gib screws.  There are several materials manufacturers use to make gibs and one is brass.  
Rich

http://warhammer.mcc.virginia.edu/ty/7x10/vault/Lathes/7x10-7x12-Projects/TaperedSaddleGibs/


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## David Kirtley (May 3, 2013)

Hi Sk8ter,

As the material for making a bearing, you are perfectly correct. As a "bearing surface" for a slow moving saddle working against a lathe bed it is fine. It is softer than the cast iron. The gib is a sacrificial surface. It wears, you readjust it. They have been using brass in this application for a few hundred years that I know of.


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## Sk8ter (May 3, 2013)

David Kirtley said:


> Hi Sk8ter,
> 
> As the material for making a bearing, you are perfectly correct. As a "bearing surface" for a slow moving saddle working against a lathe bed it is fine. It is softer than the cast iron. The gib is a sacrificial surface. It wears, you readjust it. They have been using brass in this application for a few hundred years that I know of.



Thanks for your reply....everyone has opinions 

I call  :whiteflag: 

just so everyone knows I am not here to start crap just wanted to inform and IMO this is what the forum is about

I would like your honest experience in using brass in this situation at a gib....so please carry on


Lawrence


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## David Kirtley (May 3, 2013)

That's fine. I have a very thick skin and don't take it personally. Things always sound more harsh in text than they do in person.

Initial impressions:

Once past the initial break in, I have not had to adjust them again yet. It rides very smooth and without any noticeable play. I started with just a belt sanded finish on the brass and they have lapped in. Lots of metal in the oil at the beginning.  I give it a quick squirt from the oil can each time I start using it and every once in a while as I am working on it. When it is not cutting, the gibs don't bear against the ways at all since they come up from the bottom and just keep it from lifting under load. 

It has been a wonderful upgrade but in all honesty, just about anything would be an improvement over the original system. I probably would have been just as well off with some made from delrin. The little lathe just doesn't have that much power and it doesn't take much to hold it. The little Sherlines do just fine with plastic gibs. As to the tapered gib concept itself, I can't say that it really is much better than if I had just put flat gibs and put set screws on the underside of the bracket. It was a bit fiddly to make them and they don't need frequent adjusting. Only the back one gets a lot of pressure on it normally and it is easy enough to reach for adjustment. The front gib only gets a load on the occasional time I am cutting with the spindle in reverse.  

I made a few mistakes in the process. When I made the rear gib, I cut the adjuster slot too close and the gib rides beyond it's range. Next time I tear it down, I will make a new gib to fit. It will only take a few minutes. As it is, I am in no hurry. It works fine.

The next upgrade will be the gibs on the cross slide and the compound. The ones on the compound are more of a problem than the ones on the cross slide. LMS sells a brass set already cut with the right geometry as an upgrade and I might order them if I am ordering something else or I will make some myself. I just don't have any suitable stock right now.



Sk8ter said:


> Thanks for your reply....everyone has opinions
> 
> I call  :whiteflag:
> 
> ...


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## Rbeckett (May 3, 2013)

Guys,
Not to be heavy handed or be "The Big Brother"......BUT....... This thread is an excelent showcase of a mans skill and handy work.  His selection of materials is his decision and is based on whatever research he did or did not do.  Getting into the semantic argument of the best bearing material for this particular application is POINTLESS.  He has made a fine demonstration of Gib strips that I would gladly use in my machine any time, the quality of workmanship is outstanding, the presentation is also excelent.  Will brass wear?  Yes, but so will a diamond so lets applaud the effort and boost the fellow up for  doing good work.  If he needs to replace them in 2 years or 20, who cares.....He has demonstrated his ability to make more when he needs them if that issue ever arises.  Lets get back to the original discussion and leave the material as ......imaterial.  Nuff Said?????

Bob


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## Tony Wells (May 3, 2013)

It's good that this thread has cooled off a bit. One of the founding  principles of this place is that it is different in the way  disagreements are handled, when and if they occur. In the long run, no  one generally win an online argument, and at times even enemies are made  when the opposite could just as easily be true. We want this place to  be a place where people are comfortable asking questions, giving  answers, no matter if the question is simple or complex. We have quite  the variety of experience here, and that means an equally varied set of  answers on some subjects. We expect (and the User Agreement states) that  we all treat each other with respect. Anything short of that is a  disappointment, especially if it comes from the professionals among us.  But any member should treat others as they would like to be treated, and  has the right to expect the same from everyone else. 

I'm glad that the parties involved have simply agreed to proceed with the project, and let everyone learn how this particular example works out. None of us knows it all, and it will stay that way. We simply don't live long enough. But we can make the best use of time while we're around. Have fun everybody!


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## lens42 (May 28, 2013)

Bob - Do you really think that a discussion of material is pointless? If I were planning to do this mod, and someone had info about getting better results with a different material, that's exactly the sort of thing I'd want to know about.


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## geckocycles (Jul 6, 2014)

Got my son a new HF7x12 and I have spent the last month getting it to work so he won't loose interest. Great fun project for me. I am starting the tapered gib tomorrow. Love your adjusting screws and I will use your design for that part. 

Did you have to put in a lock screw too?


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## David Kirtley (Jul 6, 2014)

No lock screw has been necessary. Other than when I have taken the saddle off, I have not even had to adjust them after the initial break in.

With the little I have had to adjust them, If I were making them again, I would forego the taper all together. Just make the holder face and gibs flat and put adjustment screws in from the bottom.


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## Shadowdog500 (Jul 6, 2014)

David Kirtley said:


> No lock screw has been necessary. Other than when I have taken the saddle off, I have not even had to adjust them after the initial break in.
> 
> With the little I have had to adjust them, If I were making them again, I would forego the taper all together. Just make the holder face and gibs flat and put adjustment screws in from the bottom.



Your tapered gibs look great!

I shimmed my gibs on the mini lathe and it worked great.

I read that the underside of the bed gets a little thick near the tailstock on most mini lathes.  Mine definitely was thicker near the tailstock, and required scraping followed by lapping of the underside of the bed to make it the same thickness all the way across.

did you run into this variation on your mini lathe?

Blue Skies!!

Chris


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## David Kirtley (Jul 6, 2014)

Shadowdog500 said:


> Your tapered gibs look great!
> 
> I shimmed my gibs on the mini lathe and it worked great.
> 
> ...



Nothing that I really noticed. I think it is just the luck of the draw. The reason these machines are so cheap is poor quality control. Might get a great one, might get a total dud, most are somewhere in between.


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## iron man (Jul 6, 2014)

This is a very good useful artical. Ray


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## DavidL (Jul 16, 2014)

For what its worth, a couple of years ago I made a set of aluminium taper gibs after the Rik Kruber design for my Chinese mini lathe.  Best thing I ever did and have no problems.  I'm retired and use my machine several hours a week.  The occasional tweek of the adjusting screws keeps everything nice and rigid.


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