"maybe I should consider covers for the end of the exposed cs ways."
Considering how much crap I find under the front bed way cover on mine, I'd think that'd be a bad idea considering the Turcite.
As for the short gib, I think the proper solution (if one is needed) is to mill the saddle to make room for a thicker one. And I don't know if a thicker gib, approaching a square cross section, could create a bigger problem with stability.
I'm not sure how serious you are, nonetheless... I find the way covers a mixed blessing. They do keep most of the chips out, but they also hide infiltrators from view. Trust me, there will be infiltrators. I'm running mine without covers for this reason. Good wipers would be better protection I think. I use Kabelschlepp. I have my doubts about felt, especially for Turcite, as it may trap fine chips.
Originally Posted by TexasTurnado
Edit: I do use front covers, but mine are shop made ones that lift off in a second.
Over the years I have seen several machine without way wipers and I installed them. Many "War" machines were built to cut chips and if they wore out in 5 years they figured the war would be over. I also install wipers on tail-stocks as many machine don't have them. I also like the Kabelschlepp wipers. I used to use Chicago Rawhide wipers until these came out. I would suggest you make a new gib from Durabar if you can't get a used or new one.
I finished the scraping on the bottom of the cs and then faced off the topside so I would have a flat repeatable surface for scraping in the Turcite:
Initial check of the flatness after milling was encouraging and a couple of passes with the scraper got me this:
Not pretty, but plenty flat enough for a precision level. Later I will either finish scraping this or send it out to be ground flat. Just for grins I rechecked the other side.... surprise!
WTF?? I only took a couple a thousandths off the other side.... Just goes to show - "Expect the unexpected"
So now I have it reflattened and ready to do the Turcite....
As soon as I saw that picture of it on the mill, and knowing it's steel, I thought 'uh oh'.
Those long gibs are a pain to scrape and get them to stay parallel You lost the original one? You may want to send the cross-slide to the grinder company and have the top ground, I seldom see them scraped. What probably happened when you put the turcite on the top of the saddle to make the gib so thin on the other end. You may have to rip off the turcite and go with cast on cast so the gib fits or machine the bottom of cross-slide so the gib fits or tke off more and put the turcite on the bottom of cross-slide. Hard to figure it out online. If I was there I am sure we could figure it out.
'uh oh' indeed! At this point, my question is: will the piece stay in this condition or will the induced stress relax over time and the piece tend to resume its original position?
Originally Posted by wesg
I presume this slight bow was caused by the heat at the cutting line causing the steel to shrink slightly when cooled - sound plauible? I would be interested in hearing comments from members who have faced this situation before.
Related question: does scraping tend to cause the same type of distortion?
The bow was unlikely to have been caused by heat from cutting. Rather, the part had surface residual stresses that you removed by milling, causing the remaining residual stresses in the part to redistribute. Scraping is also unlikely to cause measurable distortion.
Originally Posted by TexasTurnado
I doubt the part will move more with time. You could make sure by subjecting it to a stress relief heat treatment, say 1100 F for 1 hr. However, that will likely cause a lot of distortion that will then have to be machined or scraped out.
Oops, too late! Yesterday, in view of my "lesson" on warpage the day before, I set out to scrape to topside flat:
Originally Posted by Richard King
Here I have the maching marks removed and have started the spotting. However, checking the bottom side:
It has again changed, almost identically to when I machined the top side.... I was pretty sure this had happened, as before the ends were showing less blue when spotting the top side.
So now, if I again rescrape the bottom, and the moon is aligned correctly and I haven't been too bad, the top hopefully will show flatter than it does now.... and I will call it good. (at least for now).
BTW, wouldn't grinding the top side cause the same problem, but perhaps worse? When I approached Commerce about grinding my camelbacks, they really didn't want to do it....
Re-reading what I posted yesterday, I think I left out some things. Firstly, the gib is as it was from Graziano (or at least as I received it) and has not been modified. When I got the Turcite on, the gib protudes about 3/8 to 1/2 inch from where it should be, and I think this will be sufficient to allow the Turcite to be flattened and adjusted back to level wrt the bed ways.
I removed enough material from the bottom flat ways of the dovetail to bring the centerline of the cs back into alignment with its adjustment screw, taking into account the thickness of the Turcite. Only a very small amount was removed from the left sloped dovetail surface - just enough to account for wear and make it perpendicular to the bed ways.
As a result, the unmodified gib fits with contact along its full length as is (I also took a very small amount off the right sloped surface of the dovetail to make sure it was parallel to the left side).
It was an oversight on my part not to flatten the cs first, as now the Turcite is higher next to the dovetail vertex, as result of having been worn more there than at the outside edges. We're not talking big numbers here, perhaps .002 in at the most - which is fairly easily scraped off of the relatively soft Turcite (compared to ci or steel) - it's just a PITA scraping in the vertex area....
In evaluating the changes in flatness I have shown, it should be realized that the changes are measured in 10-thousands of an inch (.0001). The scraping process is very sensitive and easily shows this degree of change. To correct the bow shown in the middle of the cs after milling only required a couple of passes to correct and I would be quite surprised if I was removing even .0001 per pass.
Time to move on.....
I have had all the fun I can stand for a while scraping steel. Here is where I have stopped:
Running the probe of the test indicator around the top surface of the cs I see about +/- .0002, but some part of this is the "unflatness" of the granite plate, which is multiplied by the small base of the holder compared to the extension of the probe.
Tomorrow it is definitely on to the Turcite....
Update: Sitting here looking at this, I realized I would get more accurate readings by leaving the indicator fixed, and sliding the cs around under it - I will have to try that tomorrow....
Last edited by TexasTurnado; 01-19-2012 at 04:57 PM.
Thanks for showing your gib making process.
My two cents on a full length gib is it spends most of its life hanging out in space. This leaves it vulnerable to breakage, and tends to increase binding later when the rest of it wears a little and the end section doesn't. The only time you would get a rigidity benefit is when turning larger diameters.
Thanks for your input, Lofty. I have put the longer gib on hold for the present until I have more input and time to think about it..... Noone has commeted yet wrt using some material other than ci for the gib - I am wondering if one made of bronze would be strong enough to stay together being that long and thin.
Originally Posted by Lofty
I could make it from steel and not worry about the thinness, but I suspect that would give faster wear and maybe make it less smooth in operation than ci (thinking stick-slip here). It would be sliding on ci (the saddle), but still.....
Slight change of plans.....
I have decided to cut my losses and bow to the voice of experience: I will move the Turcite to the bottom of the cs. Even though I can be vigilant and try to keep chips off the exposed Turcite when it is on the bottom, there is always a chance a hot chip(s) will land there and melt a depression in the Turcite.
Also, my back informed me this morning it was time for a break (over the years I have crushed two vertebra, L2 and L4. but have lucked out with surgery not being required in either case), so I thought I would share with you how I aligned the dovetail on the saddle to be very close to perpendicular to the bed ways before applying the Turcite.
The following is predicated on having already leveled the bed after grinding (or scraping) and having the saddle scraped into the bed ways so its top surface is level to the bed ways in both planes (front-to-back and side-to-side).
Since any slope in the dovetail at the top of the saddle will affect the alignment of the cs with the bed ways, both sides of it must first be made level and in the same plane. I did this by placing feeler gages under the end of a Starrett precision while the saddle was on the bed and then setting it up on the mill to remove the measured amount from the high end.
After taking cuts on both flat portions of the dovetail, I put it back on the bed and verified these surfaces were indeed level. To determine the alignment of the sloped surfaces of the dovetail, I used this setup:
A piece of precision ground drill rod, known to be round and straight, was placed in the left side of the dovetail and a precision square (also known to be accurate) was held aginst the vertex of the dovetail - then a test indicator clamped to the bed way with its probe bearing on the edge of the square will indicate the degree of alignment of the dovetail wrt being square to the bed ways.
Using this info, the saddle can be returned to the mill and setup to remove the required metal. The sloped edge of the dovetail can be used for alignment in the mill, but it's slope must be taken into account when setting up. Also, be sure to take into account the distances between measurement points on both the square and the points used in the mill to arrive at the correct amount to be taken off. Only the minimum required to assure a straight surface should be taken off each side to minimize later problems fitting the gib.
After checking the alignment is as desired for the dovetail, the additional amount needed to be removed from the flats of the dovetail to make room for the Turcite can be determined. I did this by shimming the flats of the dovetail with feeler gages until the cs mounting holes for the adjustment screw nut was centered over the adjustment screw.
Subtracting the thickness of the feeler gages (all should be the same value for easiest calculation) from .050 (.047 Turcite plus .003 for the adhesive) gives the additional amount to be removed from the cs or the flats of the dovetail. I ignored the .003 for the adhesive in the subraction to give this much material for later scraping into exact alignment of the cs.
Alternatively (and as a check on the above calculation) the amount the cs is misaligned with the adjustment screw can be measured (with the cs directly on flats, i.e. no shims) and the slope of the dovetail side used to arrive at the amount to be taken off.
I just found this thread. Your work looks great so far. I'm glad you decided to re-do the turcite. When I got to the post where you did it I was concerned but I kept reading on and made it to the happy ending. Keep up the good work.
Thank you for the comments - unfortunately I already see a problem: since I cut the extra off the "wrong" side to make room for the Turcite, the gib is going to be shorter in height than the space for it. Currently, there is Turcite under the gib, but with the Turcite on the bottom, there won't be any, thus the extra space. Perhaps I can bond Turcite on the bottom edge of the gib, but that area is pretty narrow - so I may end up having to make a new, wider gib......
Originally Posted by nalambright
How hard was it to take the turcite off you did the right thing .I have a picture in the monarch forum showing the cross slide I did when Richard was at my shop it.s monarch 1940 cw