# Is my cross slide gib strip not ground properly?



## stioc (Jul 8, 2019)

This is driving me insane. If I run the cross slide all the way out (towards the operator) it gets tighter and tighter to turn. I've tried adjusting the gib screws but even with them all the way out there's a lot more friction as I move the compound towards the beginning. So tonight I decided to remove the gib strip to take a closer look.

There are two sides to the gib strip, the polished side and the non polished side (this side has a notch for one of the gib screws to catch). With the polished side down on the surface plate, there's no bow in the strip but when I flip it over there's a bow. Also the thickness on one end of the gib strip is about 15 thou less than the other end. If I try to take the bow out by bending the gib, it shows up on the other side. So I'm guessing the bow is because the grinding on the non-polished side is uneven and ultimately this bow is what's causing my issue with more friction as the compound travels outward. Any thoughts, suggestions?


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## RJSakowski (Jul 9, 2019)

Your gib adjustment sounds like the type done by adjusting several setscrews along the length of the gib rather than a tapered gib.  Since you have a bow on the back side but not the front, it would indicate that the gib is not of uniform thickness.  I suspect that a previous owner experienced the same problem and tried to modify the gib.

The bow in the gib's back side shouldn't be a factor as long as there is clearance.  My guess is that it has something to do with the lead screw.  There are two possible causes for your problem.  The backlash adjustment may be overcompensating for wear in the central region of travel causing it to be too tight at the extremes where wear is less. Or there may be a bias in the mounting of the lead screw thrust bearing.  If the lead screw isn't concentric with the nut, it will bind more as the nut gets closer to the thrust bearing.

To determine which, does the cross slide still bind with the gib completely removed?  Is there play at the front of the cross slide with the gib removed and the cross slide all the way to the front?  Do you have the same problem when the cross slide is all the way to the rear?  If you remove the lead screw, can you easily slide the cross slide along its full length of travel?  If you loosen the end cap retaining screws, does the problem go away? Answers to these questions will help you isolate the problem.

On my lathes, the end cap containing the thrust bearing isn't pinned in place.  The proper way to fasten the end cap is to bring the cross slide to the front as far as possible and then tighten the retaining screws.  This will create the least amount of bias.

If the cause is over tightening of the backlash compensation on the lead crew nut due to wear in the central region, then the solutions are replace the lead screw or loosen the backlash compensation and live with the increased backlash.  A third solution which I used on my Atlas/Craftsman 6x18 was to have a second nut which was floating and coupled to the primary nut with a spring.  This has the effect of pushing the cross slide away from the work and reducing backlash but since it is coupled via a spring, it is self-adjusting, compensating for different amounts of wear.


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## C-Bag (Jul 9, 2019)

I had a similar problem and on my 9x20 the dovetails were not parallel. It took some scraping to get them right along with scraping the gib. My compound was even worse. Most of it was in the top/female and I ended up getting a new one from Grizzley. It could use a little work too but is way better than it was. Since truing up the dovetails in the crosslide and compound my chatter and finish problems went away too. I've found there are few things you can point to on the 9x20 and say this is always the problem because even though symptom may be the same, often the cause is different. Wear and poor QC can skew things further. In my case it was worth the effort.


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## stioc (Jul 9, 2019)

@RJSakowski - thanks for the detailed response. Some answers below:
- I'm the original owner bought it about 2 yrs ago but since I rarely back the cross slide out all the way I didn't care too much about it as I had plenty of real things to learn but I think the time has come to address the issue now 

- Yes the gib has three small gib adjustment screws on the side of the cross slide, as you tighten them the gib pushes inward into the dove tail.

- Even with the leadscrew removed sliding the cross slide by hand with the gib in place it tightens up as I move it towards me. The last half inch to an inch feels like it's stuck and if I pull it hard it lets go suddenly. I'm thinking either the gib is tapered or the dove tail isn't parallel as @C-Bag mentioned. If I leave the compound slide more towards the center and with the gib screws backed out I can push and pull the gib freely. However, as I the compound slide is pulled towards me the gib strip feels wedged.

@C-Bag - I think you're on to something. Now I did measure one end of the gib-strip to be about 15thou thicker so it could be that and I can try to grind it by hand with a sandpaper on the surface plate. However, how do you check the dove tails (on the carriage or the cross slide?) and how did you grind those parallel?


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## homebrewed (Jul 9, 2019)

Dove tails are usually checked by using two equal-sized rods that are tucked into the dove tails.  A micrometer is used to measure the rod-to-rod spacing as they are slid down the dove tail.  I did that to check the dove tails on my mini mill table because I was seeing a notable increase in friction as I moved the table to one side.  

My problem turned out to be mostly due to misalignment of the feed screw bearing block relative to the feed screw nut, something much more easily addressed than non parallel dove tails.  To address that, you have to loosen the nut, run it up to the bearing block and tighten it back down.  On these machines there is just one bearing for the feed screw so that's all you need to do.


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## stioc (Jul 9, 2019)

I'm hopeful that if I sand down the back part of the gib strip the problem will be fixed. Not sure hand sanding will work or if there's a better way to do it. May be if I mount the strip on the mill using an angle plate or something and then running a drum sander disc across it. Or lay it flat on the table using mitee bites or something and then use an endmill/cutter to skim the surface.

But if I do need to make the dove tails parallel I'm guessing the easiest way for me would be to do it on my mill using a dove tail cutter. Question is what size/angle cutter will I need, is there a fairly standard size that's used by these smaller lathes?


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## T Bredehoft (Jul 9, 2019)

The thickness of the gib is not the problem. The three adjustment screws eliminate any problem of taper in the gib. If the male and female dovetails are not parallel they will cause what you are experiencing. Two years of hobby wear will not cause this, only poor manufacturing practices will.

_Edit:_ correct Typo


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## stioc (Jul 9, 2019)

The reason I suspect flattening the gib will fix the problem is because even with the screws fully backed off the gib sticks in the dovetail in the last 1 inch of travel (towards the operator).


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## benmychree (Jul 9, 2019)

It should be obvious that a gib that is set up with setscrews will not be effected by taper; from reading this discourse, it seems to me that the problem is with taper in the dovetails on the cross slide bridge.  Re cutting it on the mill is a bad idea, you may not be able to find the proper angle cutter, the angles are all over the map, as in non standard angles, and it is all too easy to remove too much material, effecting alignment.  It would be a much better procedure to re scrape  the gib side of the bridge to remove possible taper, also check the gib for flatness on the surface plate with Prussian blue or other marking medium for full bearing, it can then be used (after possible necessary scraping) to scrape in the dovetail.


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## benmychree (Jul 9, 2019)

stioc said:


> The reason I suspect flattening the gib will fix the problem is because even with the screws fully backed off the gib sticks in the dovetail in the last 1 inch of travel (towards the operator).


Still, if the dovetail was not tapered, that would not cause binding.


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## Bob Korves (Jul 9, 2019)

stioc said:


> I'm hopeful that if I sand down the back part of the gib strip the problem will be fixed. Not sure hand sanding will work or if there's a better way to do it. May be if I mount the strip on the mill using an angle plate or something and then running a drum sander disc across it. Or lay it flat on the table using mitee bites or something and then use an endmill/cutter to skim the surface.
> 
> But if I do need to make the dove tails parallel I'm guessing the easiest way for me would be to do it on my mill using a dove tail cutter. Question is what size/angle cutter will I need, is there a fairly standard size that's used by these smaller lathes?


stioc, I will add to the list and pile on that the first thing to do with that lathe is to check the dovetails, on the cross slide and on the carriage, using dowel pins that fit approximately half way into the working surfaces.  They need to measure parallel over their entire lengths.  This also tests the gib at the same time, which needs to be put in place for the testing.  The gib can be carefully straightened by pushing it measured distances and noting the results.  A gib with spring in it is a problem unless the gap is tiny.

Edit: also make sure the gib is being held lengthwise, so it does not slide and jam the gap.


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## C-Bag (Jul 9, 2019)

I think this is a somewhat common problem on the 9x20 and the reason i say that is so many folks have a failure of the crosslide housing and have to replace it or make a new one. Granted it is out of Zamak or some mystery metal. This is somewhat masked by the fact the crosslide handle is pretty small and there is no thrust bearing. Also if there is any slop it will chatter like crazy so you have to keep the gibs tight. But the fact it gets tight on one end and cannot be adjusted points to the dovetail being out of parallel. Mine was .002" tapered so I was able to scrape the two dovetails in. The compound was like .010 and I didn't have the experience with a dovetail cutter yet. So just replaced it. I don't use the compound as much as the crosslide and the little the compound is out doesn't effect chatter or finish but it's on the list. I'd suggest if you've not seen this vid go through both parts.


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## stioc (Jul 9, 2019)

benmychree said:


> Still, if the dovetail was not tapered, that would not cause binding.



Understood. I'm just hoping I can get away with just removing the taper from the gib and not have to make the dovetails parallel because I'm not even sure how that's done or if it's possible.



benmychree said:


> It would be a much better procedure to re scrape  the gib side of the bridge to remove possible taper, also check the gib for flatness on the surface plate with Prussian blue or other marking medium for full bearing, it can then be used (after possible necessary scraping) to scrape in the dovetail.



Can you elaborate on this. I'm trying to understand how to go about this as I've never done scraping (I like learning new things). To be clear, here's what I'm calling the various parts.

1. This is the cross slide aka the female dovetail
2. the gib or gib strip
3. This is carriage side aka the male dovetail


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## benmychree (Jul 9, 2019)

Bob Korves said:


> stioc, I will add to the list and pile on that the first thing to do with that lathe is to check the dovetails, on the cross slide and on the carriage, using dowel pins that fit approximately half way into the working surfaces.  They need to measure parallel over their entire lengths.  This also tests the gib at the same time, which needs to be put in place for the testing.  The gib can be carefully straightened by pushing it measured distances and noting the results.  A gib with spring in it is a problem unless the gap is tiny.
> 
> Edit: also make sure the gib is being held lengthwise, so it does not slide and jam the gap.


Bob, re read the post, this is not a tapered gib that can be measured against, it is adjusted with set screws; the only thing that needs to be measured is the parallelism of the dovetails on the carriage bridge.


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## stioc (Jul 9, 2019)

Thanks for all the replies gentlemen. I'm trying to absorb it all. @benmychree by checking for parallelism of the "carriage bridge" you mean the top flat part of the male dovetail (#3 in the pic above)? So put calipers across the bridge on the front part and then on the back part? Something like this?


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## benmychree (Jul 9, 2019)

stioc said:


> Thanks for all the replies gentlemen. I'm trying to absorb it all. @benmychree by checking for parallelism of the "carriage bridge" you mean the top flat part of the male dovetail (#3 in the pic above)? So put calipers across the bridge on the front part and then on the back part? Something like this?
> 
> View attachment 298103


No, I mean as Bob Korves and others noted, take two dowel pins of a diameter that hits the dovetail angle about half way up and measure over to pins at both ends of the dovetail, and in between the ends to detect taper in the dovetails.


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## stioc (Jul 9, 2019)

Got it. Something like this...now to find dowel pins...


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## benmychree (Jul 9, 2019)

stioc said:


> Got it. Something like this...now to find dowel pins...
> 
> View attachment 298108


Yes, just like that; if you have some drill rod, that would work too.


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## Cadillac (Jul 9, 2019)

As others have stated the thickness of the gibb on this style doesn’t really matter. The sliding surface needs to be straight the variance will be taken up by the adjustment screws. Although it would help to be parrallel. 
Looking at your picture of the gibb installed it really looks like the angle on the gibb doesn’t match the angle on the cross slide and the gibb is tilted to match??
The height of your screws could be a problem tilting the gibb. 
Sanding the gibb or machining the gibb will most likely make it bow being so thin. 
 I e gone through the cross and compound on my 9x20 and almost done with my 14x40. Scraping all surfaces making them flat and correct. I’ve put oil grooves on flats and dovetails of all surfaces with oiling ports. Doing this made a 100% difference on the 9x20 and see it doing the same for the bigger lathe. Both compound and cross slide top had a slight bow. Suspect the cast wasn’t seasoned well and sprung when machined. Absolutely no hand fitting of pieces surfaces were machined and flaked to give the appearance of scraping but once put on a surface plate it told the story. Qi is not their strong point for sure. It’ll take some time and effort good luck on your journey.


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## stioc (Jul 9, 2019)

The reason I say thickness matters in this case is because without the gib strip there's no friction (the slide is very loose of course) and even with the screws completely removed the gib strip sticks in one spot. This spot also happens to be the thicker part of the gib strip. So if I were to grind it down flat I think it'll resolve the issue of stickiness.

I just need a surface grinder...this is my scheme to shoe horn a surface grinder in the shop somewhere- even been shopping for one on craigslist for the past few hours but they take up a good bit of space which I really don't have much of https://orangecounty.craigslist.org/search/sss?query=surface+grinder&srchType=T

Besides, scraping is well beyond my knowledge and skills and I'll probably make a bigger mess of it


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## Cadillac (Jul 9, 2019)

it is very possible the thickness is the culprit. You need to check the dovetails male and female to know what your dealing with. Without the top installed place the gibb on the cross slide does it rock in the dovetail or are the dovetails correctly matting?
 I wouldn’t rush getting a surface grinder for this job. You don’t want to rush purchasing a SG and it’s not cut and dry grinding a thin gibb like you have. Without coolant know how and some talent it would be more warped than what you started. Believe me I’ve been dabbling in the subject of grinding thin metal and it’s not easy and just happens going through the steps. 
  Get some measurements and map it out to see what you have then come up with the best solution.


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## stioc (Jul 9, 2019)

Thanks. I will do that, most likely tomorrow-  if I can find some dowel pins.

FYI, the pic of the cross slide I posted earlier is not mine, it was just to clear up the terminology.


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## Ulma Doctor (Jul 10, 2019)

if you had the inclination, you could lap the gib flat on the offending side.
simply dunk a sheet of 150 grit wet/dry sandpaper in water and put it on a sheet of plate glass.
be careful to not add too much pressure while lapping, the metal should come off rapidly.
clean the gib meticulously with alcohol or acetone to remove sand, grit, etc.

scraping would be another method


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## AGCB97 (Jul 10, 2019)

I know leadscrew was mentioned briefly, but I would look very close at it and the nut for rust, dirt, damage and alignment. Seems much more likely.


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## RJSakowski (Jul 10, 2019)

Have you tried bluing the surfaces, looking for high spots? Clean the oil off all the surfaces and use a magic marker to coat the surfaces.  As you move the mating parts, the coating will rub off the high spots.  

If you have eliminated issues with the lead screw and you are experiencing problems at only one place, I would suspect that the problem is due to a non parallel condition of the dovetails with either the cross feed or the cross feed saddle or both.  Measurement with dowel pins as previously described should show which.  

A gib of this type should be a loose fit.  The set screws make the clearance adjustment.  The sliding surface needs to be flat but the back surface should be a non-contact surface so curving or a taper shouldn't be an issue.  If you find that you have a binding situation  the back side can be thinned down by filing or lapping.  Presumably, you are only looking at a few thousandths at most.


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## stioc (Jul 10, 2019)

Ulma Doctor said:


> if you had the inclination, you could lap the gib flat on the offending side.
> simply dunk a sheet of 150 grit wet/dry sandpaper in water and put it on a sheet of plate glass.
> be careful to not add too much pressure while lapping, the metal should come off rapidly.
> clean the gib meticulously with alcohol or acetone to remove sand, grit, etc.
> ...



How will this remove a taper though? Let me illustrate my question with my MS Paint skills:




If I flip the taper side down on top of a sand paper, apply even pressure and sand it, it will simply keep removing the same amount of material across the entire length i.e. the taper will still be there the same amount but the gib will get thinner overall.




This is where it has to be ground flat on something like a surface grinder.


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## RJSakowski (Jul 10, 2019)

If you apply pressure to the thick end, the thin end will float and the bulk of the material will be removed from the thick end.  Take frequent measurements and don't take off more than is necessary.  A few thousandths should do it.


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## stioc (Jul 10, 2019)

I did have a few mins last night and managed to find some dowel pins. Before anyone asks, the micrometer body was interfering with the measurement that's why I used the calipers. So the carriage side is dead on parallel:







The cross slide side had a .006" variance but it was hard to measure so I need to redo it when I have some more time. But again, I wouldn't know how to fix this issue of removing the .006" from the back. If I remove it from the gib at least it won't stick and I can do the adjustment by the set screws. Remember that it sticks even with the set screws completely out.


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## stioc (Jul 10, 2019)

RJSakowski said:


> If you apply pressure to the thick end, the thin end will float and the bulk of the material will be removed from the thick end.  Take frequent measurements and don't take off more than is necessary.  A few thousandths should do it.



In the absence of a surface grinder I'm thinking of creating a fixture and using it with the belt sander. The idea is that the gib will be captive in a slot (so it can't move up or down) but allowed to move side ways. I will put this jig against the belt vertically and simply pull the gib across the belt taking a light pass or two.

Here's the slot I made the gib sits flush on the thinner side but starts to protrude up where it's thick, as it's pulled across.


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## stioc (Jul 10, 2019)

Another question, are gibs of this sort hardened? I'm wondering if I can just mill it. I can make a magnetic fixture of some sort and just mill it flat.


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## markba633csi (Jul 10, 2019)

I'm pretty sure the factory messed up making that gib,  it should have been straight not tapered.
Since you have a mill, why not make a new one?  Brass is easy to work with and makes a good gib

Mark


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## stioc (Jul 10, 2019)

I don't think I have the tooling to make beveled cuts on long strips. I can make some fixtures- just a bigger project. I'll try the sanding or milling first and may be take on the gib making project when I have some more time.


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## T Bredehoft (Jul 10, 2019)

Lets try something else. Assemble the compound on the cross slide. Leave out the gib. By hand, run the  compound in and out. It should be free all the way both ways. If not, figure out why, (dry everything, paint one piece allover with felt marker. slide them together till they bind, disassemble and see where it rubbed.)
I there was no bind, put the gib in big end to the back and see what that does.  Is the dimple in a position to catch a set screw?  If so, put it all together and see if it binds.  Check it anyway, even it the hole doesn't line up. 
That way you'll know if the gib is the problem. 
Exhaust all posibilities before changing anything permanently.


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## stioc (Jul 10, 2019)

@T Bredehoft I will try what you suggested, I should have some free time tonight. However, I did do a couple of those things previously:

1. No stickiness without the gib strip
2. Yes the notch is for the front set screw to sit in that way when the cross slide moves the gib strip also moves with it.
3.  I think when I flipped the larger end towards the front of the slide the angles didn't line up. I think the angle on one edge of the gib is different from the other edge so it only wants to go in one way.  I'm fuzzy on this so I will re-check tonight.


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## homebrewed (Jul 10, 2019)

I have read accounts of folks making their own gibs out of steel, brass, bronze, and acetal.  So it's very unlikely your gibs are hardened.

Edit:  I made the Fignoggle fixture for making gibs and used it to make some brass gibs for my mini mill.


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## stioc (Jul 10, 2019)

That's cool, I'll have to try making one along with a fixture to hold the gib at an angle. I have a few ideas in my head how I'll do it.

If the gib I have is in fact unhardened I think I know how I will mill it. I also want to try grinding it with the fixture I started building for the belt sander. I need more bad gibs to play with lol


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## RJSakowski (Jul 10, 2019)

The gib should be softer than the ways.  It should be the wear item as it can easily be replaced.


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## homebrewed (Jul 10, 2019)

stioc said:


> I need more bad gibs to play with lol


You could always make your own "bad" gibs  

BTW the fignoggle gib-fab fixture holds the gib at an angle so it's easy to get the parallelogram shape.  But that moves the problem to milling the properly-angled slot in the fixture.  To make mine, I made a 34 degree angle block, put it in my angle vise and used a DTI to adjust the vise angle.  Once the DTI needle stopped moving I knew I was good to go (I'd NEVER trust the protractor scale on a cheap imported angle vise).

If you've got a sine table and gage blocks, you've got it made in this regard.

When I made my version of the gib holder, I moved the hold-down screws to the other side of the slot.  Reason:  I thought the forces on a half-finished gib could make it "tip" over.  The one drawback:  you have to make sure the screw heads clear the top of the vise that's holding the fixture.

To avoid marring the gib, I put some brass shim stock between the gib and screws. 

The drawing for the Fignoggle gib holder is in their free plans section.  You can't download it but you can print it.


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## stioc (Jul 11, 2019)

OK guys. So here's what I did yesterday. I decided to use a Dremel type grinding stone on the mill but in order to do that I had to hold this thin gib strip flat and supported but also open at the top. I don't have a magnetic vise/chuck but I do have those cheap Harbor Freight magnetic tool holders. I put that in the vise on top of a pair of parallels, then indicated off the edge of it and then laid the gib strip on top. This was surprisingly secure, in fact, in the end it was almost impossible to remove the gib strip but I was able to slide it off. I also used the sander.










What worked and what didn't work:

1. The small grinding stone was dissolving way too fast to be trusted to create a flat surface. Next I tried Roloc as I didn't have anything else.
2. The Roloc even the most aggressive 100 grit pad left a fantastic finish (very polished) but wasn't removing material fast enough. It also wasn't digging into the material when I moved the z-axis to say .01" at a time because of the soft pad material. Lastly it generated a lot of heat into the part so hopefully I didn't work harden the gib strip. So this would work great for a polished finish (or removing rust/milscale like it's usually used for) but not so much for sanding metal.
3. The belt sander removed material the fastest. I'm sure if the jig could be refined to use a magnetic slide or something it would work fairly well. In fact, knife makers on youtube seem to use something similar quite successfully as a poor man's surface grinder.

The end result? It worked. I can now run the slide all the way to the back and to the front very smoothly and evenly using the handwheel (which btw sucks due to it's poor design but that's another story). No play in the cross slide when I tugged on it while in both extreme in and out positions so I'm very happy with the results.

Thanks to everyone for your help and suggestions, hope I provided some entertaining value here if nothing else


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## homebrewed (Jul 11, 2019)

That's some clever usage of what you've got on hand!


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## chip maker (Jul 11, 2019)

So in the end you got alot of good information and ended up doing just as you had thought to fix your problem. That is one thing I have always liked about this site. Many will give the best ideas even when just getting the info that is given them as close as possible. As some did giving you how they fixed a matching problem but at the same time giving good info as to how to how to come to the best fix.  Good people always willing to help. !!!


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## stioc (Jul 11, 2019)

Yes that's what's great about being part of a like minded community where we share ideas, problems, successes and failures. I'm glad the simpler fix addressed my issue otherwise I wouldn't have known how to go about scraping and making dove tails parallel 

Thanks for following along!!!


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## RJSakowski (Jul 11, 2019)

I always feel that answers given have a twofold purpose.  One is to give advice to the OP but the other is to put information out to the group for those who might run into a similar problem.  

One of the great things about the internet is that no matter what you are trying to do, most likely someone has already done it and posted the how-to.


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