Square vs dovetail ways?

[wrmiller]

I can see the advantage of tapered gibs. My inexpensive Asian tool has dovetails with flat gibs held in place with screws. The adjustment of the pressure on the gibs
greatly affects backlash. Is it possible to convert to a tapered gib? and how might this be accomplished?

Thanks

I've been thinking along this line as well. I 'assume' I would just have to take one of the two pieces comprising the dovetail (like my lathe compound) and re-cut one side to a taper. Gross oversimplification, but you get the idea.

Bill

 

[DMS]

If you re-cut the dovetails to take a tapered gib, just make sure you cut the right half. Also, if you are doing it in a really small machine (like a 7x mini lathe) be aware that you don't have a lot of material to work with, so be careful about depth of cut. You will also need 2 adjusting screws on the front and back of the gib to adjust it. If you have access to a machine with tapered gibs, it is instructive to pull the gib out, examine it, replace, and re-adjust. I didn't really "get" how they worked until I did this with my mill, but afterwards it was like "duh".

I have been under the impression that box ways were the "better" deal, and were only used on higher end machines. Course, I have never seen a machine with box ways in real life.

 

[wrmiller]

If you re-cut the dovetails to take a tapered gib, just make sure you cut the right half. Also, if you are doing it in a really small machine (like a 7x mini lathe) be aware that you don't have a lot of material to work with, so be careful about depth of cut. You will also need 2 adjusting screws on the front and back of the gib to adjust it. If you have access to a machine with tapered gibs, it is instructive to pull the gib out, examine it, replace, and re-adjust. I didn't really "get" how they worked until I did this with my mill, but afterwards it was like "duh".

I have been under the impression that box ways were the "better" deal, and were only used on higher end machines. Course, I have never seen a machine with box ways in real life.

I have a bit more material on my SB, but thanks, point taken with respect to depth of cut.

I also was of the same impression as you about square ways, as I've only seen them on the bigger BP clones like the 10x50. Maybe they're primary purpose is to support the extra weight these machines might see?

 

[Richard King]

I can see the advantage of tapered gibs. My inexpensive Asian tool has dovetails with flat gibs held in place with screws. The adjustment of the pressure on the gibs
greatly affects backlash. Is it possible to convert to a tapered gib? and how might this be accomplished?

Thanks

A number of years ago I was rebuilding a Goss & Deleeuw Machine it was a cam fed special machine that had a turret and 3 boxed way slides with spindle heads. Anyway the customer asked to convert it to tapered gibs to make it faster to adjust them when they wore. These machines were in a company that made water facets out of bronze and they were constantly filthy with coolant and chips. So the gibs needed to be adjusted a lot more then and these square gibs were a pain to get at from the sides where with a tapered gib usually has one adjustment screw on the back side and the screw fits in a notch or has a L shaped end with a hole throw it and a jam nut on each side of the L to keep it from moving. Other's have a screw on each end, but if the machine has lots of swarf adjusting the front gib screw can be a pain.
We had to widen the opening in the head stock slide way that rode on the base box way that was flame hardened (grinding the base was a pain and another story sometime). I bought some Dura-Bar and Then made an insert with one side tapered and the other straight to rest against the widened original surface. We epoxied it and bolted in place usuing the original holes that had been the adjustment screws. We made the taper in our Bridgeport with 3 Kurt vises mounted on the table and adjusted the taper using a dial indicator and made it .008" per inch taper. I picked that number as I believe that's what Cinc. Centerless grinders use and it is another Heavy Duty casting machine that wears a lot. We machined the insert in the same way. We scraped the tapered insert face and the back (positive) of the gib to 5 PPI but flat to .0002" per foot as sit is what we call a static fit and the riding surface of the gib to 20 PPI and flat .0002" per 12". We also relieved the center of the riding side of the gib middle 40% .001" and cut oil grooves in it.

It was an interesting fix. I hope that makes sense. I am sorry no pictures anymore. Just memories. I would think one could use the same method to convert a lathe compound. You might not need the tapered insert and only machine the slide tapered and have a wide gib. If you did that then I would think you would either have to use a front and back adjustment screw or have a .032" sheet metal support under the front side of the gib to keep it from tipping down. Remember what your dad said thought measure twice and cut once. I would also draw up some plans before hand. No guessing or in your mind blue print on this one I hope this helps. Rich

PS: It's 2:45 AM over here and Im having a real pain sleeping. I can't understand how some people can work swing rotating shifts. It would kill me. :whacky: LOL

 

[David Kirtley]

I can see the advantage of tapered gibs. My inexpensive Asian tool has dovetails with flat gibs held in place with screws. The adjustment of the pressure on the gibs
greatly affects backlash. Is it possible to convert to a tapered gib? and how might this be accomplished?

Thanks

Depends on if there is enough material on the piece. I can't say that it would perform much better. The gib strips with screw adjusters on the dovetails do a pretty good job. I converted my saddle to tapered gibs just because the stock adjusters are awful and it is miserable to get to them to adjust. I have thought about putting some of the aftermarket brass gib strips on my cross slide and compound but I have somewhat sworn off modifying the lathe in order to actually spend some time making things -- for a while.

 

[wrmiller]

All good information folks. Thanks!

 

[Richard King]

I have some brass or bronze scrap, will gibs made of this perform better than the steel ones that came with the machine?. I scraped those flat and it seemed to make a difference but they didn't have any oil grooves. Will adding oil grooves make a difference? Would it be better to make the gibs of brass/bronze AND add add oil grooves?

Thanks

Sure....how else will the oil move down the gib? be sure to slot the back of the gib so when you move it the oil will flow. You should know this my friend as you are a sharp cookie Use a diagonal oil grove where the end where the oil flow through the gib it drains down. Some manufactures also bevel like a funnel the top of the gib and the oil runs down off the flats and into the oil gove. be sure the groove does not open at the bottom edge as the oil will just drain out. You can also 1/2 moon flake the gib or square cut it. Rich

 

[wrmiller]

I bought some bearing bronze for just that.

I think the plan is to model my new compound in aluminum to get a feel for cutting dovetails and tapers therein. The only dovetail cuts I've made previously was to mount a Bo-Mar rear sight on a 1911.

Bill

 

[markknx]

I have Box ways on my Jet 15 with a wedge gib. It seems to work nice and is easy enough to ajust, but at some point the wear for up and down would seem to have to be addressed. I am guessing that the only way to do this is by removing metal from the clamping plate where it meets the bottom of the way, or the bottom of the way itself. But as a begginer I am just guessing and hopping someone will tell me/us if this is right or if there is a different method.

Thanks,
Mark

 

[4GSR]

Mark,

I'm not familiar with the Jet 15 mill. But with what you are saying, most of the wear is in the upper mid range of the slide.

Traditionally, this is common wear for most any slide arrangement rather it being dovetail or box ways. To remove this worn area is not a simple task of removing material from the clamping plate. This just adds to the "slop" in the slide, which will show up in the machining process to some degree.

This is where scraping and re-fitting needs to happen. I'm sure the slides on the Jet mill were originally ground and the slide portion was scraped and fitted to the box member. I won't go into detail here its rather a lengthy detailed subject on scraping and fitting here. There are many threads dealing with this subject that may be of interests if you want to lean in that direction.

If you feel comfortable removing or maybe shimming up the clamping plate with brass shim stock, this maybe your best bet for the time being until more is learned about machine restoration.