Thats a big hump! Looking good though
Now my workshop is back in shape after doing my lathe DRO I'm back at it with the grinder. Got the main casting round out of the van and stripped down. Contrary to what is says on the Lathes website the casting for the type 3 is in 3 pieces (in fact if you look at the image above where it says 'one piece casting) you can actually see the joint. Nice Whitworth thread fasteners so despite being very rusty they just came undone.
This is going to make it a whole lot easier to scrape and then paint
Mines only 2 castings from memory
The dovetails look as though they've been built up with bronze, or is that just a trick of the light?
Nah they've been built up with rust
Actually it's just staining but the camera really shows it up. The column ways despite 'looking' pretty rough have no detectable wear. Not surprising since the Z-axis is barely used on a grinder. It moves into position then increments fractions of a thou at a time.
Here's a short vid showing a rough check-over with a DTI.
https://www.dropbox.com/s/5v9y0bu9iz77khd/Eagle Grinder Column.mp4?dl=0
It'll be getting a light scrape in any case same as all the other working ways. There's some surface rust on the never-used bit at the bottom.
Wow, that looks flat as already Pete
Just need a quick touch up with the Biax.
No scraping tonight. I've been using a wire wheel to clean stuff up and that puts too much stuff airborne which messes with the printing. I did a bit of painting and cleaned up the mating faces of the three parts. Surprising that there was a full film of rust right across the joint, as if there's a significant gap there. I'll check it with a surface plate to make sure there's no raised corners.
I used a dead flat carbide scraper to cut off the rust and leave behind the machining marks. Often what looks like a really rusty part cleans up just fine - even lathe ways come up ok so long as it hasn't started pitting. Using a dead flat scraper is risky though - it's very easy to put a deep gouge in the face with the corner of the blade.
After scraping off the rust I go over it gently with a soft wire wheel just to clean off the remainder. Don't want rust particles tearing the surface of my plate up.
Today's work was to strip all the paint and rust off the outside with 4" belt sander, flap discs and wire wheel. Wire brush the whole inside by hand and put the base and column in primer. It was a lovely day here so I took the opportunity to warm the castings up and quickly move them outside for painting.
After that I set about scraping the column. As usual I went over it a couple of times without any blue to break up the surface, or the blue just smears. That's why you see scrape marks in the pic below in the low areas. Then I started bluing it up and scraping down the high areas. In the pic the column top is nearest. As you can see there's a couple of low spots at the far end where the weight of the knee causes the greatest load (plus the ways pick up dirt which grinds away at the metal). The wide strip down the middle is inconsequential as it isn't used, but it must be scraped so the plate I am using spans the whole width.
I've no idea why there is a big low spot at the top middle. Probably the casting moved a little over time, or maybe it humped a little during machining from heat.
Getting there. The two dips were deeper than they appeared to be when I first swept the face with the dial gauge, but they are nearly out now.
And this is how it is now. Good enough for me. A funny thing happened, I cleaned my plate and switched to using an oil-based spotting blue instead of the water-based one. The oil-based stuff shows up better when it's thin and the lights were making it hard to see. As soon as I did that it started to print a lot heavier in the middle. I left it with a slightly heavier print as it doesn't affect the working parts of the ways - the middle isn't used.
Tomorrow is a nice day again so I want to get the two sides scraped in quick in the morning so I can bolt the column on the base and wheel them outside for painting.
I spent the morning scraping the main column dovetails and getting masked up for painting. The dovetails were a bit of a mare because they had unworn ridges that I had to get rid of but I wanted to get this into paint so I got stuck in. I fixed the column to the base, masked it up then put a 2kw infra-red heater inside the base whilst I was masking the other bits. By the time I was ready to paint you could hardly touch the casting
I hate painting and usually ends in disaster so with great trepidation I pushed the lot outside into the alley and mixed up some Ferguson dark grey and 25% xylene. The actually sprayed quite well and I'm super-happy with the results. Normally I can consider it a minor victory if the paint actually hits the object I'm shooting at.
Got pretty good coverage and no runs that I've spotted yet on the castings. Some of the smaller bits came out a bit rough, mostly because I didn't have time to heat them and also because the ally bits (apart from the handwheels) I had already painted silver but then decided it was too bright but this grey wasn't too happy about sticking to the aerosol silver. On the whole it's pretty good.
Right now I'm swapping between running the two heaters. One is hanging on a mag base on the ceiling for heating the hanging parts and the other is
cooking the base casting at about 60 degrees
Tonight's work - make a new z-axis screw. The old screw is 1.125" diameter 10TPI LH ACME with 15" of thread. And it's knackered. The end is rusted so it will chew up the nut and the one most used spot in the middle is worn razor thin.
First I turned a plain end at 1" diameter. It'll finish at .750" but I wanted it bigger to get a good grip in the collet.
Then I turned the OD to 1.225". This is .100" bigger than the original. I'm cutting the thread 100 thou big so I can turn the nut out and cut a new female thread. No sense looking for a large piece of bronze when I can cut a new thread in this one just by going bigger on the OD. With ACME thread the double depth is 1/TPI" so with the pitch at 10TPI the double depth is 1/10" or 100 thou. Hence, 100 thou bigger.
Set the ACME tool square to the work.
Lubricate the precious leadscrew
The first cut is ALWAYS made with a sharpie. I had the stud and box gears set for fine threading so this would have been a 40TPI instead of 10. The sharpie trick saves you ruining the part.
And cut the new thread.
I made a bit of a novice error by not backing off the tailstock and re-setting it half way through. The part warmed up and tried to grow in length. It couldn't so it started to whirl a little which made it grumble in the middle of the cut. Luckily I realised and let the pressure off before wrecking it. I took the revolving centre out for the last couple of spring passes and used a dead centre with the speed turned down.
Just got to do the nut now, that'll be fun
Good tip with the sharpie, that will save many a part from the scrap bin.
Z axis nut is all bored and threaded.
I had to knock up a quick & dirty boring holder for the insert. It wasn't great but it did the job and held up fine.
That's nearly it for the screw I have to turn the plain end down to .750", make a woodruff cutter to cut the key and then drill & tap the end for the securing bolt. I might just cut a straight keyway in it I don't see what harm it would do.
Some more progress today. Boring the nut out had removed the oil catcher groove in the end of the nut. There's an oiling point up on the knee so I presume that the oil runs down the thread and pools in the groove to lubricate the screw so I cut a new one then installed the nut and screw on the mounting plate.
I cleaned up the telescoping cover for the screw and fitted that along with the z-axis thrust bearing.
Then I built the knee onto the machine, fitted up the rise & fall gear, shaft and handle. Lots of cleaning and re-greasing involved and a bit of time setting up the gib for the knee. Then I did the same for the y-axis screw except it's only fitted temporarily as I have to make a new nut. Strangely the screw is almost perfect but the nut threads are worn to knife-edges.
And that's how it stands right now. As you can see, the handles I ordered from Axminster (eventually) turned up. They are acceptable quality and I'm glad I bought them instead of trying to make some, even if they were a bit slow shipping. They set the cleaned and painted handwheels off nice.
Tomorrow I'm going to finish the last of the scraping (the cross table y-axis ways). These are the worst worn ways and I want to get them done. I only have one week now before work goes crazy for the next 6 months.
Looking really good Pete, whats the first project? Fancy making some precision stones like Roberenz and Abom use?
Hadn't given it a thought yet Paul. I keep hearing about those 'precision stones' but as I'm not an avid youtube watcher I hadn't looked into them either. I guess there's times when I could have done with a stone that was thick enough not to bend but flat enough to get a big aggressive with to increase bearing or fix it when I over-scrape something.
So I set about fixing the badly gouged Y-axis ways on the table. The ways were scored and worn uneven plus the nut land in the middle would have been high after scraping down so I decided to fly-cut the ways and the nut land rather than struggling to scrape it all. I put the table in my little Herbert mill, which unfortunately doesn't have enough y-travel to cut right across plus it's badly in need of a rebuild so I made my best effort at fly-cutting it in two setups.
This is all I could get from one side. After that I turned it around and cut the last little bits from the opposite side (got no pics though).
After that I cut a relief groove along where the gib bolts on. This is to make it easy to scrape the way flat right across - without it I would have trouble making sure the straight edge sat flat.
First print came out not too bad. Better than I hoped for.
A couple of scrapes with the biax and it's coming in. There are a couple of deep bits where I ran the table right up to the stop, causing it to ligft on the last little bit which would be less worn than the rest.
This photo is showing where I use the Biax to scrape the blue and avoid the bits that didn't print.
After a couple more rounds I decided that I'd had enough. There are a couple of small areas left but there's plenty of bearing now.
Looking at the damage that the Y-axis had suffered (and it was the only way that suffered it) I decided to do something about the fact that they put no facility in for getting oil to those ways. Everywhere else has oil nipples so I thought about how I could pump oil to the ways. On the front of the table are two stop bolts that screw into holes. These are quite close and above the ways so I thought I could use these as an oiling point.
I drilled as far in as my longest appropriate diameter drill would allow.
Then marked out the table at the drill depth.
And drilled down at the 30 degrees to make the holes meet.
I suppose I better show where I messed up too. I didn't think about the well for the table rack being deeper down the middle than the table thickness on the outside. Didn't occur to me until this happened..
But it was soon fixed with some epoxy mixed with cast iron dust (to stop it drooping down the hole as it set).
It's all set now and the oil passage is still clear.
Last thing to do was some oil-flaking. I got out the Biax flaker and set about cutting oil pockets.
I haven't really used the flaker at all except to test it so I'm going about it very gingerly. Just doing one layer in the one direction. Flaker cuts deeper than the scraper and so the pockets last a lot longer. Their job is to hold oil that would otherwise just squeeze out between two flat surfaces.
The other way isn't so pretty because the dovetail makes it very awkward but I was determined to get some good flakes in there to hold the oil.
Good job Pete, at least you will be sure you are getting oil to the ways now.
Thanks Scott. Can't believe there's no way to lube the ways under all the covers.
After that I started to cut a new y-axis nut. The screw is in fantastic condition but the nut is worn to a knife-edge. It would still work but the handle has huge back-lash. The 1" diameter bronze nut is set in a cast iron housing and held by a grub screw.
I'm making the nut from an old handwheel shaft from a water main valve I smashed up on a demo job. Not sure if it's bronze or a very hard brass but since it was a hard-wearing part it'll last me out I'm sure. I turned and bored the blank before packing up for the day.
Not looking forward to attempting to cut this thread. It's a 3/4" diameter 5TPI LH ACME. That means the bore of the nut is only .560" diameter and 1.800" long The thread depth is 100 thou plus I need a bit of clearance so I'm going to have to try to cut it with a home made tip set in a bar that's no more than about .400" ( 10.16mm) diameter and even then I'm going to have trouble with it packing with chips.
I'll have a couple of cracks at it and if I can't get it right I'll have to make a tap.
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