On the vices and joys of machine tool reconditioning...

[ttrikalin]

That'll work!

Dave

Dave, our posts crossed. Yes, I think this will do it. 

[ttrikalin]

Officially, the first component to be completed (apart from the bed, which was ground last year  ) is the compound cross slide. The bearing surfaces on the lower side are very flat and mark up pretty nicely on the plate. The upper surface is not parallel to them though. 

-----+    +----+
    A |     | B   |
       |     |      |
    C |     | D   |
-----+    +----+

In the photo below, points A and B are at the same height, and so are points C and D. A and B are 0.001" lower than C and D. Connelly says the difference should be 0.

Note also a little 'hole' or 'valley' at the inner edge, between B and D. 

So I am scraping C and D down. 

[steamer]

Tom,

Make a few passes staying violently away from the edge of the master.   As a matter of fact take two passes staying about 1/4" away from the edges of the master.   I ran into this scraping my angle master in that it's really difficult to mark it without influencing it.  I believe your crowned in the middle ....if the middle hollows out, you'll know where you are.    As it sits, you need more coverage up to the edge to reach the inside of the dovetail accurately.   

I resorted to making a flat master to mark up the angled master.   This was from a Master Scraper at Moore, whom I brought the master too to check my work.  He said these small masters can be tough and that was the way he recommended to fix it.

I would try to hollow it out a bit so you know you sitting on the periphery.   Then let the bearing progress towards the center. 

Tough bit, but keep going!.....


Dave

[ttrikalin]

After some scraping' the updated height differences have equalized quite a bit:

I am calling this OK for now -- we are within two tenths 
 


Note that this leveling is not critical; the lathe tool does not pivot or move on this surface.  It marks decently for now.

[steamer]

And we're talking two crossed passes here....don't go back to roughing it...just relieve it a bit to make sure it's not crowned.

Dave

[ttrikalin]

Tom,

Make a few passes staying violently away from the edge of the master.   As a matter of fact take two passes staying about 1/4" away from the edges of the master.   I ran into this scraping my angle master in that it's really difficult to mark it without influencing it.  I believe your crowned in the middle ....if the middle hollows out, you'll know where you are.    As it sits, you need more coverage up to the edge to reach the inside of the dovetail accurately.   

I resorted to making a flat master to mark up the angled master.   This was from a Master Scraper at Moore, whom I brought the master too to check my work.  He said these small masters can be tough and that was the way he recommended to fix it.

I would try to hollow it out a bit so you know you sitting on the periphery.   Then let the bearing progress towards the center. 

And we're talking two crossed passes here....don't go back to roughing it...just relieve it a bit to make sure it's not crowned.

OK, will do this first time I go down to the garage these coming days. Thanks for catching a possible error!

I will continue posting what I did till tonight, with the understanding that I will have to re-check after the master has been checked and remastered!

[ttrikalin]

The (to be remastered master) with a lot of blue on it and the back screws in place (will make appropriate insulated handles... )



And the compound slide, with the internal dovetail ready to be touched:



And this is the touchup. You cannot see it clearly, but it has a 'hole' in the distal front. The tip in the front colors for one and a half inch, then there is a valley for 1 inch or so, and then it colors.



I removed some blue and repeated, and then very lightly touched it up with the scraper. 

[steamer]

It's hard to say for sure Tom, but a small change in procedure like I described, if it is flat will POP right away, and you'll only be a cycle or two away from being flat and Knowing it.

Just trying to prevent you chasing your tail like I did....

Additionally, don't handle that master to much.   Your hands will make it move around from thermal effects, and you'll go back in the morning and find a different result and wonder why.....ask me how I know this....


Dave

[steamer]

Our posts crossed again....NICE HANDLES!

Dave

[ttrikalin]

It's hard to say for sure Tom, but a small change in procedure like I described, if it is flat will POP right away, and you'll only be a cycle or two away from being flat and Knowing it.

[...]
Additionally, don't handle that master to much.   Your hands will make it move around from thermal effects, and you'll go back in the morning and find a different result and wonder why.....ask me how I know this....

Excellent points.
Next time in the garage I am fitting insulated points handles , and I am checking that the center is not crowned as per the test you described!.

Pending this check all today's posts are tentative...

[ttrikalin]

By the way this is the imprint on the master after the touch up.

[ttrikalin]

And after 4-5 touches and light scrapes this is the best photos I could take (very light blue on the tone remastered master). Left part of the dovetail:



Right part of the dovetail:

[ttrikalin]

Next task did not involve ay scraping, just marking up for the swivel base upper surfaces...

The upper bearing surfaces mike within a tenth of the basal surface of the part at various points throughout their length. 

As per Connelly, I am going to be using the basal surface of the compound rest as a template, and the master to do alternative markups to plan my scraping.

Here is the template, and next to it the part in its wooden holder.



Touching up:



Wipe pattern on the template:



and imprint on the part...  one side



and the other side



Hmm    Not sure how to think about it...

Next post is the touch up with the to-be-remastered master...

[ttrikalin]

And this is the touch up with the master...



And this is marking the other side... (Shoot, I did not get a photo of the first side's imprint on the part... you may be able to see it here though)



and this is a good view of the one side, and not a good view of the other...



I have to think about the geometry here... and may haps do measurements on the surface plate...

[ttrikalin]

And a couple of tools...

This is nice for putting blue on dovetails... a small 45 degree prism with a piece of leather JB welded on it.  Got it from Peregrin's website... www.metalscraping.com. I bought his CD, it has good materials. I learned stuff.