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Tony
01-05-2014, 03:30 AM
Yes typing that subject line hurt me just as much as it hurt you -- but no turning back now. :)

For anyone interested I took the plunge and have my first reference surface brought back in.

In addition to sharing, I also have a question -- the dovetails on this table are tiny! 1/2" tall.
Before I reinvent the wheel, what does the tool look like for working in there?

Eyeglasses screwdriver with brazed carbide tip? :)

comments/crits always welcomed of course.


http://youtu.be/RjwKQCiDgBQ

coldformer
01-05-2014, 06:50 AM
just another wannabe with a camera are you a machine rebuilder or tool maker? buy a machine clean it up lube it then after you learn how to use it then i will be interisted in your rebuild

Peter N
01-05-2014, 07:56 AM
just another wannabe with a camera are you a machine rebuilder or tool maker? buy a machine clean it up lube it then after you learn how to use it then i will be interisted in your rebuild

I think you posted in the wrong forum, here's a quick re-direct for you: http://www.practicalmachinist.com/vb/.
It's his machine, let him get on with it. I think he also has some support in his endeavours from Richard King, which is not a bad thing at all.

dian
01-05-2014, 08:14 AM
great video, tony, as always.

Tony
01-05-2014, 10:01 AM
hey I'm willing to take one on the chin every now and again;
but good point though, I should have clarified:

In the interest of full disclosure, I am not a machine rebuilder or
a tool maker. For that matter, I'm not a machinist or a welder, either.

wierdscience
01-05-2014, 11:01 AM
Into every life a few jackasses fall-that's how I see it.

I think your doing good Tony,I don't get CF's point,just how are we supposed to learn if we don't start somewhere?What you have done so far can only improve the machine.

buffdan
01-05-2014, 12:56 PM
Nice progress Tony!
Thanks for sharing your work..
I am sure you will have a nice machine when you are finished.

You are giving encouragement to others who are considering refurbing their machines.

Dan

dian
01-05-2014, 01:33 PM
could you explain the geometry of the pull scraper, please.

Alistair Hosie
01-05-2014, 01:48 PM
I liked your video tony .There are always some people that appear never to be happy so pay them no attention keep the good work up and have a great new year Alistair

Tony
01-05-2014, 01:54 PM
i first ran across the pull scraper in this youtube video. french/swiss, perhaps? I've since read
they are referred to sometimes as 'european' style or simply 'pull' scrapers.

Here is the video. I tried it in HSS but that required sharpening too frequently and I brazed on
some carbide (old inserts, any variety, as long as the size is about right)

http://www.youtube.com/watch?v=TFCVO0fXW1k

I find myself mixing it up between pull and push scraping. I have an anderson style that I ground
a large radius into.

For a beginner.. at least for me.. I found the pull scraper much more controllable when trying to put
a lot of power behind it. Also simply bending at the knees or standing up straighter altered the angle
of attack to get the correct "scrape" without affecting the power of the stroke.

In contrast to the push style scraper where, if you don't get the blade geometry correct, you may
need too high of a push angle to get it to cut properly.. and if the angle is too high then it gets uncomfortable
(or unreasonable) to push.

Again, just my personal learnings there.

J Tiers
01-05-2014, 02:57 PM
In addition to sharing, I also have a question -- the dovetails on this table are tiny! 1/2" tall.
Before I reinvent the wheel, what does the tool look like for working in there?



How about this, if the picture is clear? I had trouble getting a pic that showed the shape. Basically it is a scraper with one edge, and the other ground off into a "barge nose". I used this one for the Rivett dovetails.

http://img.photobucket.com/albums/0803/jstanley/tooling/scraperdovetail_zps9aa480c7.jpg (http://smg.photobucket.com/user/jstanley/media/tooling/scraperdovetail_zps9aa480c7.jpg.html)

mattthemuppet
01-05-2014, 05:40 PM
very impressive, especially for being self-taught (as far as I can tell). I learned an awful lot about the process and the measurements that go into it, thanks! One quick Q - when you get down to spotting then scraping, do you scrape the blue dots, clean and re-blue? Or is it more "scrape a little bit from everywhere then re-measure"?

TGTool
01-05-2014, 06:02 PM
very impressive, especially for being self-taught (as far as I can tell). I learned an awful lot about the process and the measurements that go into it, thanks! One quick Q - when you get down to spotting then scraping, do you scrape the blue dots, clean and re-blue? Or is it more "scrape a little bit from everywhere then re-measure"?

It can be some of both. The blue areas are high plateaus, so in theory you scrape them off to try to get everything down to one level. In actual fact you can use some reasoning and analysis to speed things up. So you know the blue is high and the not-blue is lower, let's say .0004" for discussion. So somewhere out past the blue but not in the lowest section it will be .0002" lower. Knowing this, you can scrape away the blue once and an area slightly larger is scraped twice before you check with the surface plate again.

Later in the process when blue areas are fairly evenly distributed, you can address just the blue, then later yet taking maybe half the blue. What this does is to get more spots and smaller and smaller areas evenly over the surface. And there are rules of thumb for how many big or little spots in a square inch. For two surfaces bolted up together you don't need a really refined surface. For moving ways it gets finer and for gauges, finer yet.

Tony
01-06-2014, 11:02 AM
TGT hit it on the nose.

The tough bit for me was keeping everything parallel to the reference face. I "wasted" quite a few scraping rounds getting things
flat but slowly 'tipping' the surface out of parallel. I eventually got a handle on this by forcing myself to rotate the work 90* on
every pass. Not just my scrape direction, but the actual work on the bench. Not sure what kind of ergonomics went into it but
having the work always in the same orientation resulted in me "tipping" the surface.

JT: picture is perfect & worth 1000 words as they say. I have to find some thinner carbide tips.


Update: the "saddle" is turning into a real head scratcher. The only bit even remotely resembling a reference
surface are the tops of the male dovetails. These are original (unworn) surfaces, but they're just the machined casting.
I can use those to keep track of "parallelism" but I'm going to have to take some measured guesses of 'perpendicularity'.


The bottom of the saddle (dovetails to the knee) are pretty darn worn too so using those would result in just
as much "guessing".

If I did both (top and bottom of the saddle) i suppose it wouldn't be a problem -- but for now I only want to
do the table.

mattthemuppet
01-06-2014, 11:20 AM
interesting and thanks for the detailed answer. Now I understand the references to "spots per square inch" that I see in scraping posts. I guess that having mating surfaces with a slight texture (as opposed to ground smooth) also helps retain oil and allow them to slide over each other. Looking forward to the next installment.

Tony
01-07-2014, 07:22 AM
Question for the gang -- I've measured the wear in the dovetails, both under the table and on the saddle.

Under the table: 0.0215" wear -- the female dovetails "diverge" in the center. this is 0.0015" on the fixed, cast iron
side, and 0.020" on the steel gib side.

On the top side of the saddle: 0.008" wear, from outside male dovetail to outside made dovetail. More of the 8 thou
is on the gib side, than on the CI-CI side -- but I don't know how much -- my straightedge rocks more thats all I can
say.

So I have 0.0135" of material "lost". (0.00215"-0.008"=0.0135")

Does it make sense that I'd have more wear on the steel gib side than on the cast iron side?

Best I can tell most of the wear has happened in the steel gib itself. (0.020"!) -- over 24".

J Tiers
01-07-2014, 09:01 AM
How are you measuring?

What size pin are you using to get the measurement? Should preferably contact in about the middle.

Also, using pins with a female dovetail is tricky IF the guide surfaces are not all on the INSIDE.... commonly it is the inside of the dovetail, and bottom surface, so the inside adjacent surface is not a guide surface, and isn't a good reference. The pin is affected both by the dovetail surface, AND the adjacent surface... for the situation above, you have to hold the pin in relation to the actual guide surfaces.

Tony
01-07-2014, 10:02 AM
JT, thanks for quick reply. Yes I'm using pins that contact 1/2 up the dovetail face. In my
case this is 8mm pins.


I do realize both faces of the dovetail affect the "width" measurement -- though it wasn't
immediately obvious, this was one of those 'a-ha!' moments while I was having breakfast
one day and thinking of the next steps I'd have to do on the grinder.

I'm not scraping yet, just trying to get order-of-magnitude wear and where its located.

That said I'm simply dropping the pins in the dovetail angle and measuring with a
home made "dovetail gage". In the case of 55* degree dovetails, and 0.010" wear on
one of the dovetail faces (where pin touches) this equates to about 0.007" error in
width reading.

Its a cosine or sine error (over 55*), I think, but in reality I just laid it out on paper (CAD).

So my measurements are *underestimating* the width wear -- if I've got that right.

Nonetheless, almost all of my wear is in the steel gib and its mating dovetail.

Does that make sense? Or am I totally off base here.

Here are some pics of the dove-tail-o-meter:

http://img.photobucket.com/albums/0903/knucklehead/machineshop/grinder/gage1_zps99a2a818.jpg

http://img.photobucket.com/albums/0903/knucklehead/machineshop/grinder/gage2_zps2218c2a7.jpg

J Tiers
01-07-2014, 07:54 PM
Well, The measurements are not "bankable" until one of the surfaces is known to be flat..... When both are unknown, all you can tell is that there is a problem.... What you come up with will be a combination of the errors in both

Then also, as you know, the bottom of that male dovetail is not a reference (guiding) surface, so vertical movements will affect at least the indicator side. Small ones will be in the noise, though. It would take about 6 thou vertical movement to change the measurement by a tenth, if you start out precisely on the correct spot on the cylinder. 12 thou vertical would get you about a half thou in equivalent horizontal measurement error.

Still, on a non-precise surface, you might have 6 thou or even 10 or so thou of variation,.....

And, what goes for the top goes equally for the (worn) flat way. You had 10 thou on another part, so possibly a similar amount on this flat way. That will change your measurement a half thou right there, PLUS any random stuff due to the top surface

I'd use a mic on it. The larger flat anvil makes it easier to measure. And you can keep it flat relative to the flat ways.

dian
01-08-2014, 04:22 AM
do you know nicks dovetailometers?

http://www.youtube.com/watch?v=esAqz6bCVyQ

http://www.youtube.com/watch?v=AzhmMp2fLSw

J Tiers
01-08-2014, 08:34 AM
I do not see why the micrometer must fail.... unless the structure gets in the way, as it appears to in the first video.

And even then, one can use a parallel spacer block to contact the cylinders. Then there would be very little trouble. But I have not had that problem, the mic always works fine for me so far.

You do have to be careful to get it stright, but the same is true of the "dovetailometer".

Tony
01-13-2014, 09:14 AM
for anyone interested and not subscribed (tsk! tsk!), part 2 is up.

this installment is a bit more measuring and then working on the gib.

as always, comments / criticisms welcomed.


http://youtu.be/1mfz2lJRSHo

Richard King
01-13-2014, 04:26 PM
JT, thanks for quick reply. Yes I'm using pins that contact 1/2 up the dovetail face. In my
case this is 8mm pins.


I do realize both faces of the dovetail affect the "width" measurement -- though it wasn't
immediately obvious, this was one of those 'a-ha!' moments while I was having breakfast
one day and thinking of the next steps I'd have to do on the grinder.

I'm not scraping yet, just trying to get order-of-magnitude wear and where its located.

That said I'm simply dropping the pins in the dovetail angle and measuring with a
home made "dovetail gage". In the case of 55* degree dovetails, and 0.010" wear on
one of the dovetail faces (where pin touches) this equates to about 0.007" error in
width reading.

Its a cosine or sine error (over 55*), I think, but in reality I just laid it out on paper (CAD).

So my measurements are *underestimating* the width wear -- if I've got that right.

Nonetheless, almost all of my wear is in the steel gib and its mating dovetail.

Does that make sense? Or am I totally off base here.

Here are some pics of the dove-tail-o-meter:

http://img.photobucket.com/albums/0903/knucklehead/machineshop/grinder/gage1_zps99a2a818.jpg

http://img.photobucket.com/albums/0903/knucklehead/machineshop/grinder/gage2_zps2218c2a7.jpg


I tend to agree with TJ here. Showing your method is not the normal way we Pros' use.

Have built the machine up from the top of the knee and now doing the top of the saddle? The experienced scraper scrapes the flats (both sides) parallel to the top of the knee and then the dovetails. From the above picture you have not scraped the flat and you should before making this test. Have you checked to see if the flats your gage is setting on is parallel to the flat ways and parallel to the bottom? The way you should do it is to scrape the flat ways first and make them parallel to each other and then scrape the dove-tails. I know we talked about both ends measuring of the table and the ends are, but this being the saddle it is done in a different method. The "Order" you should follow is do the flats first and then set you gage on those flat ways and measure your dovetails. I can send you pictures of the King-Way Gage my Dad invented and it rests on the flats and measures the dovetails. Your way could have errors in it if clearance top surfaces are not not parallel to the flay ways. Lets say you scrape the dovetails parallel and then scrape the flay ways and one end is higher or thicker and you scrape it lower. then the dovetails will get thinner on that end as you go deeper into the angle of the dovetail and you will have to rescrape your dovetails again. I tell people to use those clearance surfaces as guides to check from, but unless you know for sure they are parallel to the flat ways it's not a good method. Rich

Tony
01-13-2014, 05:34 PM
Thanks Richard I appreciate your input.
I would've imagined that my procedure is unconventional -- simply because I've never done it before and am
working through it in, essentially, complete isolation.

However, in the 2nd installment I explain the reasons behind the way i'm doing it and that there is error in
the dovetail width measurement -- its just a first pass 'survey' of where the wear is -- big picture, as it were.

I do know the error in the flats of the dovetails and have calculated the error that imparts on the width error.

Once those surfaces are scraped to the master i'll repeat that measurement in order to repair the dovetails properly.

At least that's the theory. :)

Tony

Richard King
01-13-2014, 06:49 PM
Tony,
We are helping....not being critical....Your doing fine just trial and error for you now. JT and I have gone down your road and are just trying to help and save you some time. Sometimes it's hard to write and not sound critical. I know my kids always figured they were smarter then their mom and Dad were.....and sometimes they were right but most of the time if you asked them now we were right. Scraping and rebuilding has a learning curve as does life.
I watched your You Tube and emailed you some comments and sent some photo's of a mini King-Way showing how we measure from wear surfaces of ways and not clearance surfaces. Keep up the good job. Rich

J Tiers
01-13-2014, 07:19 PM
I certainly didn't intend to be critical.... I've made enough mistakes myself, many when I thought I was doing right.... and I've had to re-do things due to oversights. Just mentioning it to save you trouble later.

As for the King-way.... it's a goodie, you need one. What it really does, aside from the level vials, if you choose to add them, is to provide a frame that allows most of the measurements needed, like the ones illustrated in the Connoley book on machine rebuilding.

Some pics of the one I put together a while back.... as illustration of use and construction. level vials not shown.

A representative measurement... tailstock flat way vs carriage ways. (this measurement actually gives less info than it might seem)
http://img.photobucket.com/albums/0803/jstanley/kingishway1.jpg (http://smg.photobucket.com/user/jstanley/media/kingishway1.jpg.html)

Checking the angled surface of a column dovetail vs the front face.
http://img.photobucket.com/albums/0803/jstanley/kingishway4.jpg (http://smg.photobucket.com/user/jstanley/media/kingishway4.jpg.html)

The "runner" for the V and dovetail surfaces
http://img.photobucket.com/albums/0803/jstanley/kingishway5.jpg (http://smg.photobucket.com/user/jstanley/media/kingishway5.jpg.html)

The "runner" for flat surfaces (you use one of each for most measurements). I used a "tooling ball" and a fabricated washer, because I have lots of tooling balls available. The ball fits in the countersunk part of the washer to give a good "slider", but the ball can be used alone when that's a nuisance.
http://img.photobucket.com/albums/0803/jstanley/kingishway8.jpg (http://smg.photobucket.com/user/jstanley/media/kingishway8.jpg.html)

Tony
01-14-2014, 03:10 AM
Thanks guys! I sure hope I didn't come off as defensive; quite the contrary, I really appreciate your
feedback.

Richard I did get your email and the pictures -- looks like JT made one of his own. I'll have to digest
that a bit.

I'm not doing the column or the knee because:


1. the table-saddle was much more of problem in practice -- the table didn't have its full travel therefore
I couldn't even grind in the mag chuck!

2. they're much more difficult :) (you're starting to throw perpendicularity into the mix)

Once the table is straightened out I'll do some grinding and see how much of a problem the other two
axis are. This is only home shop stuff -- and little stuff at that. With a little luck the column and the knee
won't have too big an impact on what I need from the grinder.

Thanks again to you both.

Tony

Peter.
01-14-2014, 04:46 AM
Nice one Tony. I'm just starting on my t&c grinder which has a 20thou taper on the table dovetails. Bit easier than your job as the alignment is not so critical but it's still had me scratching my head.
Keep up the good work!

Richard King
01-14-2014, 08:04 AM
Tony I was thinking your gage would work as long as you lower and raise the indicator to check top dead center of the pin and not take a reading as it sets on the clearance surface. The reason I mentioned checking while the machine is assembled is the weight factor causes things to sag a bit, so making your final tests and bluing before scraping should be done when assembled on the machine and not on a plate.

The home built King-Way looks good, about the size of our model HK-100....after the patents expired everyone and his brother copied them. I have parts for them, but because it so easy to make everyone made them and it wasn't practical or profitable for me to mass produce them anymore. I have 2 regular sized ones I have bought used, this model the HK-200 is the one we sold more often and will I be selling them on Ebay in the next few days. I have been thinking of selling "kits" but to spend hours to make pennies makes me less willing to do them before I retire. Thanks for doing the You Tube video's and posting here. It's fun reading and watching them. Rich

J Tiers
01-14-2014, 08:29 AM
....

The home built King-Way looks good, about the size of our model HK-100....after the patents expired everyone and his brother copied them. I have parts for them, but because it so easy to make everyone made them and it wasn't practical or profitable for me to mass produce them anymore.

OOPs.... I'm one of the "everyone and his brother".... Actually, there are so few of them around that they aren't very available, they seem to go for premium prices... and I don't "do" ebay anyhow. It probably never was much of a mass-market, and less so now that "nobody pays to repair anything".....

Mine is probably smaller than an HK-100, I totally free-handed it, no "scale". The castings were filed from steel lumps. Tubular "runner" is about 4.5" long, I don't know how that compares with the actual unit sizes.

Rosco-P
01-14-2014, 08:36 AM
In use, wouldn't Tony's "dovetail -o- meter" suffer from parallax and affect the readings? What part or parts of the frame prevent it from skewing as it's moved along the surface? Doesn't Mueller Nick show a similar device in one of his scraping vids?

Not a dig, just trying to understand the principals and the process. Seems like all of us (well many of us...) are all trying to learn the lost arts, only to have them lost again when we hang up our shop aprons for the last time. Wish I had had the balls to barge into a scraping shop I passed in Springfield, Ma many years ago and ask them to teach me. Shop was dark, dusty and looking idle then. I'm told they finally closed up after one of the owners passed away.

Richard King
01-14-2014, 03:26 PM
This forum sure is so cool how we help the other members. There are several methods that will work to test the parallelism. Tony is experimenting with this method and I have discovered for years we all have opinions and want to try our own contraption every now and then..ha ha. I personally wouldn't use his dovetail-o-meter, but I have tools that were passed down to me from my Dad who taught me and he was taught by a German immigrant who probably was taught by his father over in Germany... Tony is being a detective and learning with trial and error. I congratulate his ingenuity in making his gage's. I also like the way he double checks his techniques. He is doing an amazing job for a beginner and on his own means out in the beautiful hills of Italy. You are correct Rosco on the the deflection or parallax (had to look that up in the dictionary, ha ha). That is why the King-way clamps tight and it's channel slides along the surface and doesn't twist (much). If he had a Cylindrical grinder he might be able to grind a ball into the center of his right side pin so he could do a top dead center plus side to side center check. Way to complicated when a mic over the pins would work or a surface gage that is shown in the Connelly book, K-way, etc. Happy Scraping......Rich

Richard King
01-29-2014, 11:54 AM
How is the rebuild going?

Tony
02-17-2014, 05:00 PM
Rich: too slowly! I'm having a great time but I'd rather be grinding.

(there's a bumper sticker in there somewhere).

For anyone following, the 3rd installment is up.

Any suggestions on how to better evaluate how square my saddle dovetails are, I'm all ears.

I'm thinking I really should get Connelly's book. Other part of me thinks I'll pay much more attention
to his book after I've done it the "hard way" maybe.

The bit about measuring the squareness comes in at 18:45 for anyone who might want to skip ahead.

Though I certainly recommend the whole thing, it'll keep you on the edge of your seat. :)


http://youtu.be/WcIkjhJv_oM