Preparing machine for scraping

I have this G&L 25RT borer here that I was just wanting to tickle up the bedways a little bit... They are not worn very much, but enough so that with the gib adjusted at the most worn area, it is tight at the ends... I may end up doing all the bed ways...

It is all box ways, and is constrained vertically only on both sides of the left side box way where the leadscrew is...

What I am wondering is how to prepare the machine for scraping in so far as getting the base level.. The machine has eight jacking screws under it..



I have the horizontal underside of each box ways as an unworn area... And I have one vertical side of the right side box ways that is also unworn and could be used as a reference for straightness (hard for me to explain)



So what I want to do is level the base as it was when it was in the factory being made... I only have those small underside horizontal shears to use to level it up... Well that is as far as I know anyway... If it was sitting on a planer or bed grinder it would be very easy... Just run a dial indicator along them and adjust to 0-0 or so....

I will have to use a level.. Any ideas?

I had this set up here.... scraped square with a square level stuck to it... A frame level would probably be preferable.. Is that what one would do? Use something like a frame level and level along those small underside shears? Or is there some simple easy trick to do?

OK, ...

How much will this bed bend under its own weight? Close to nothing. It is a relatively high structure compared to length.
But knowing is better than guessing.
Put the bed on screws (at the 6 places I see). Leave the middle ones without load. Put a level on the end of the bed. Screw the middle screws up until the end screws are almost unloaded. See wether the level moves.
IF no
Screw all bolts up to at about same load (you could do that with a torque wrench and a little guesstimating of weight distribution)
ELSE
use level on the underside and the bolts to get the same reading all over the length.
END

My guess is, that the bed will twist (more than it sags). So check for twist.

Preferably, do tighten the bolts during work. That might result in having 6 useless bolts in your shop floor in case you move the planner.


Nick

I suppose Richard will be along with a definitive answer, but just thinking of the concept... you could literally scrape it to any combination of the levelling bolts loaded in an infinite number of possibilities. But I think the one that you want is to try to level and scrape it right where you use the machine, IOW, don't move it afterward. Just to add, as the machine is built up with its own components and thinking of any heavy workpieces...make sure each bolt has some sort of contact with the floor so as its loaded there is uniform support.

Along with what Nick said also check the vert alignment of the column, to make sure its not way out of wack. it looks like you have a kind of King-way alignment tool that will help you check for twist. other ways of checking this would be with a tight wire and a wire Mic or microscope. One other feature to look for on the bed casting are machined flats that seem to have no useful reason to be there they are most likely factory leveling pads, leveling the machine from these pads would put the machine in the same state in which it was manufactured and checked when it was made.
Cheers Don

Everyone is making a lot of sense..:-) 3 Pro's and a semi pro ....I enjoy reading and hope to someday to just read. I told John Sidecar another Pro the other day to help as I'm am thinking I'm a blabber mouth..lol
I would set the machine on some steel plates say 1/2" to 3/4 (or what's handy) x 6 x 6 and spot face the plates to accept the leveling bolts. I would bet the bed is the same as a lathe bed, the ends are almost original and show little wear? I noticed the home made King-way too, and as Nick said I would get both ends level and the twist out on the almost original ways. Then work toward the middle. The original KW has 2 bubbles but if you only have 1, use a level to check concave or sag and I would bet wear.

If it has been sitting twisted a while you may want to get it straight and let it sit there a few days and see if it moves. I would also wring the casting to help stress relieve it. Sounds nuts but if you hit the casting with a 10 pound mall all around on the outside it will vibrate and move the molecules around. I also tap on the leveling Screws to seat the plates and screws in the thread.

The hold downs are usually not worn as the saddle drops down. The scored ways look like the backs of the column where the hold downs are, I've seen this before on the backs of columns..??

It's getting late, so I won't write much more tonight, plus I have a headache. Maybe from the thread about sharpening machines...I took some asprin. But thanks for asking so we can all get off that other thread.

Another thing that Matt brought up is correct about when you add the saddle and table will the bed change. When i was in Taiwan at YCM they had issues like that. They would grind the base then scrape the saddle and table on the machine, then set the column on and everything would change. So they mde up a weight they set on the area where the column set to compinsae. But as Nick stated The G&L design of internal support ribbing is one of the best designs, they use a diamond design with a circle there too. sort of <>O<> hard to draw ...but Rich look inside the column and you will see what I mean.

When I was growing up we scraped many a G&L as they were made just a few hours away. I would also play detective and make up a sketch and draw up what everything measures now. Then as you scrape the saddle and table check the 4 corners with a surface gage and indicator to keep it going up parallel. Bed time....more later. Good night friends. Rich
One more thing be sure to keep track of how much you scrape off the bed as the feed screw and shafts will bind up if you do not.......to tired to think now.....Rich

Thanks everyone.. I will get into it in the near future...

And in these now (in)famous words.....

...to be continued!

Yes to be continued...

Cut some 200mm X 200mm X 12mm plate squares, countersunk a tad in the centre... Leveled machine up.

Using this device, measured the outer vertical shear in reference to the unworn shear (which was checked for straightness) The figures on the bed if you can read them is in 0.01mm's I put a 5mm gauge block under the DTI to average out the scrape marks..




If I get them parallel, then I should keep the spindle close to parallel as well... I rough checked it here within reason ..




As the bed is worn the DTI should follow the curve in the bed (as the ball dips down, the dti will indicate a deviation from parallelism even though it in reality isn't or shouldn't be).... It did so I am taking it at this stage to be not out so far, if at all..

I am at the stage where I can trust my scraping to not dig big holes everywhere, and if I take off a pass, it will be pretty even.... So with this in mind I just step scrapped the areas the DTI told me were not very worn...

I have not got it straight within 0.02mm and I have grabbed the 5ft straight edge, and will now work on getting it straight and parallel with the unworn side..

Do you have the top flats scraped and finished?

No because this time around my goal really was just to have it so the gib would not be tight at either end... it is going to be a half arsed job I know...

I do not have the time at the moment to do a full rescrape on the machine.. So I was just going to do the vertical shears, then put it back together and I have a couple of jobs for it...

That's cool....looks good so far.... How did the leveling go....Was the machine leveled before and you were using it? Or did you buy it used and brought it into your shop? If that's the case, did it have a twist in the bed? You may want to take your level and set it on the bed and then set it on the top of the spindle as it is probably hanging down low at the bed side from gravity and wear, be sure to lock and unlock the head too. Lock it when your indicating it. . If it's hanging down, the side will be off a bit. It's been a while since I have scraped a G&L but the side your scraping and the opposite side or the side on the shaft side is the guide side right? And the gib rides in the inside ? or is it where the King-Way channel slide is? I like the idea of using an unworn surface or clearance surface that was machined at the same time as when the gib and positive opposite gib side to use as a master to get the worn side straight. I would trust that before the spindle because it is worn and the way is original. Thanks for teaching and sharing. Rich

The leveling went fine... I purchased the machine second hand, and have only just installed it... As you mentioned previously the casting is very stiff, there was no noticeable twist in the bed... I am not 100% happy of it's current position... I my shift it at a later date and bolt it down... That way the machine can be leveled properly.. And yes the guiding way is as you describe, with the gib on the inside... I did read somewhere in some book that with way design, you have the guiding way close to the leadscrew that moves it.. To prevent binding...

I will admit I am struggling at the moment, besides the cold weather is annoying me, trying to mark up with a 5ft straight edge which is not light holding it flat is not easy.. In fact I am concerned I am possibly rocking the straight edge so the shear is being scraped round... Plus about five spottings and my shoulders are aching... I do not know what it weights... 60-80lbs I guess...

I have tapped a small hole in the centre of gravity on the straight edge and have it suspended from above, but I am finding it is not a satisfactory solution...

I am going to use my much lighter 3ft straight edge on it I think, but it has done a contorsion of it's own and requires re scraping...

Did I mention the cold weather is annoying me? I hate cold weather...


damn cold weather...

I would use the lighter SE and indicate the side and keep it parallel . Picking up a heavy 5' SE is a good way to get a hernia and back problems. I usually hang them with 2 nylon straights at the airy points or have a helper. I get a kick out of what you call..

Cold weather???
I checked and it's 66 F there today.

Rockhampton, Queensland Forecast | Weather Underground

If that's what you call winter, don't come to MN in the winter

Here is what the temp in the winters on my deck and Grandpa taking his Grandson sledding in the winter.

RC99 said:

Did I mention the cold weather is annoying me? I hate cold weather...

Click to expand...

Don't make me laugh. If it's above -10C, it's not cold.

PDW

Richard King said:

I would use the lighter SE and indicate the side and keep it parallel . Picking up a heavy 5' SE is a good way to get a hernia and back problems. I usually hang them with 2 nylon straights at the airy points or have a helper. I get a kick out of what you call..

Cold weather???
I checked and it's 66 F there today.

Rockhampton, Queensland Forecast | Weather Underground

If that's what you call winter, don't come to MN in the winter

Here is what the temp in the winters on my deck and Grandpa taking his Grandson sledding in the winter.

Click to expand...

Sorry for the slow reply, I saw your photo's and had a bit of a dizzy spell... You will be pleased to know currently outside it is 6.6C or 44F.. No wind and it is actually more bearable then when the wind is blowing.. Going to be frosts in the morning for sure..

I am going to use the lighter 3 footer now.... Did a print and all looks good... Weighed the 5 footer.... just over 80 lbs...

I know I'm stating the blindingly obvious here but that bed would have been rotated onto it's side for scraping in the manufacturers workshop. The same with the column, it would have been laid down for scraping and the bedding on of the spindle frame. They would then be supported on stillages or trestles to avoid excessive deflection of the castings. That's were your workshop slingers and crane drivers ( riggers in the US ) earned their corn. Anybody with a fair amount of common sense should be able to lift machinery and large components straight up and down. The skill in slinging/rigging is being able to rotate and manipulate large pieces of vulnerable machinery precisely without damaging them.

I did know one of the top floor borer ( 40 ft high columns ) guys at " Asquith " very well and he assured me that for the final fine scraping/tuning of the columns the scraper guys were suspended in a large weighted bucket off the overhead crane !

Regards Tyrone.

I know I'm late for the party but I thought I'd throw it out there as much for my own feedback as anything, but for this particular style of machine I'm not sure I personally would be as concerned about how it was levelled in the factory, and instead set it up to minimise the amount of material that would need to be scraped off. I'm going to assume a map of the bed would indicate more wear at one end compared to the other, so it could finish up that the bed was actually set up to be very slightly tilted when compared to when it was originally scraped.

Hopefully that makes sense and I'm not completely talking out my clacker, it's just my 2 cents on how I would personally probably approach it. I'd be grateful for feedback if there was anything especially wrong with that thought process.

G'day Pete.

Where you will run into problems with that approach, is on the underside of the ways where the retainer / keeper plates go. That's the ledges on the underside of the main way, where the plates bolt to the bottom of the saddle. They wear less than the top of the way, that's taking all the weight. And as you wear the way, the retainers drop, making clearance on the underside.

That's a shit of a surface to scrap, because you are working upside down. That underside will be closer to original. You get some wear there, but not as much as the top. In rough scraping, you can often just chase the retainer face, by measuring with a micrometer, bringing the top down until its parallel, so you can set your retainer snug.

So if you bias your levelling so you have less to do on the top of the way, you end up having to do more to the bottom of the way. I know which one I'd rather scrap. Its the one you can do standing up.

Regards Phil.

(On edit) You can see the way I'm talking about in R.C's very first pic. Its that land that looks about an inche wide, on the underside where his tri-square is sitting

That's very true Phil, I hadn't fully considered that part of the equation. It's why I follow these threads so carefully, even though I'll probably never rebuild this particular machine, the thought process often translates to other situations. Thanks again.