[Vogavt]

I've read many forum threads, purchased the handbook of scraping (which is just a collection of extracts from older publications) and looked over the internet for topics on scraping.

Nowhere have I found information on the order of which surface gets scraped first or second. I would think there should be a logical sequence. Don't know.

I started by checking the dovetails on the column first and was surprised as to what I found. There appears to be a single line of contact along both the gib and the dovetail.

I don't think it's a burr because I believe that would then only show on one or the other not both.

So, can anyone speak to their own experiences?




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[luv2ride]

I would read through Ryans g0704 build thread and get some ideas. Start with a LOT of measuring and decide where to start from there. Depending what is out of alignment will help give an idea where to start I would think.

[Vogavt]

Thanks! I just took a quick look at the link. Missed that one. Some good information there.
I just wished the pics were still there. Would have been more useful as the old adage says.... thousand words....

[luv2ride]

I thought it was just taking forever to load them...hmm. His pics were worth a thousand words as well and may be a little confusing without them.

[Vogavt]

I right clicked on the default image (where the pic was supposed to be) and copied its URL.
Pasted in an new tab and I'm getting the 403 error (not 404 where the page doesn't even exist).
It appears (or disappears in this case) that the image has been removed from the imageshack site.

Yeah, I think I really need to see some pics to get a sense of what's going on.

That's the problem with this hobby, by the time I get around to doing some wonderful things that others have paved the way in, all I seem to get is "Nothing to see here folks, move along"! LOL!

[SCzEngrgGroup]

My guess would be you had a small piece of foreign material on the ways. There's no way you really have that kind of contact, but whats in the photo could easily be caused by a single small piece of debris, like a single grain of sand, on the ways.

Regards,
Ray L.

[zakuhn]

My guess would be you had a small piece of foreign material on the ways. There's no way you really have that kind of contact, but whats in the photo could easily be caused by a single small piece of debris, like a single grain of sand, on the ways.

Regards,
Ray L.

Saw this post. I have an X2 and I saw this exact problem. It's hard to see/track down, but here is the reason this happens:

First, I'm going to be talking about the X axis. Everything also applies to Y-axis.

Prior to the gib being inserted between the dovetails, inspect the fit of the table to the ways. You will notice that the underside of the table has a huge gap to the top of the dove tail. Now slide your gib in. It will be nowhere near a tight fit. Additionally, notice where your gib screws press on the gib itself. It is nearly the same height as the top of the dovetail ways. The top of the screw actually applies force ABOVE the top of the dovetail on the ways. What this ends up doing is applying a rotational force to your gib. Instead of applying a straight even force to the gib, it applies a rolling force until the bottom of the gib presses against the dovetail on the table (or if you are looking y-axis gibs, on the base). Additionally, the gib height does not match the gap height between the table and ways, and the width is not the full width. This lets the gib lift up when the rolling force is applied until the whole thing finally wedges against the dovetail on the top edge, and the table on the bottom side of the gib. That line you are seeing is where the top edge of the dovetail is actually the thing making contact with the gib instead of the face of the dovetail.

The only (easy) way I can see to correct this is to remove material on the "top" area of the gib where the gib screw will(would?) contact the gib to lower the point of pressure the screw applies to the gib, and therefore remove the rotational force.

simple ascii art:

_______________
         __   /
  __ x  /  / /
     / /  /  <--- gib screw applying force here. Top of screw impacting above top of ways dovetail, causing rotation , Line seen from edge of ways dovetail at point x
    / /__/  /________

_______________
         __   /
  __ x  |  | /
     /  |  |  <--- gib screw applying force here. Top of screw impacting above top of ways dovetail, causing rotation , Line seen from edge of ways dovetail at point x
    /   |  |/________

I'm also machining new gibs out of brass that are closer to full height/width of the space available (and brass so slide better).

I made a jig at the correct angle so it is easy to just throw some brass bar stock in and mill the gib top and bottom at the correct angle. If you end up wanting a set let me know.

[TroyO]

My general approach is to flatten the largest ways first. I check for gross misalignment first but if it's even close I go ahead and flatten the largest planes first. (Usually base and table ways and dovetails) Check alignment (parallelism and co-planar) Then you can fit the smaller surfaces (usually the saddle) to those long planes easier than the other way around. But I am no pro and have only done a g0704 and a X2. It worked pretty well that way in both cases.

[Gregj888]

If you can get a copy of the Home Shop Machinist series on scraping, it covers the X2 mini-mill in detail.

Order.
Top and front of the table first, they become your reference surfaces. This also really helps later doing setups. Good square generally gets you right on.
Then work from top to bottom and you can make most of the measurements from the spindle.

It takes a little time but is well worth in IMHO. Very happy with mine < 0.001" full travel X,Y and Z.

Don't forget the column attachment. I have the tilting column and it's much stiffer after scraping.

BTW, I got a copy if the article when I was about 2/3rds done. I stopped and did top and front of the table and was surprised to find them within my 0.001" across length of travel. So I can say the average is pretty good, though all the pieces had a bow (about the same distance high on both ends).



Greg

[TroyO]

If you can get a copy of the Home Shop Machinist series on scraping, it covers the X2 mini-mill in detail.

I read that series too. Very nice read indeed. (I even special ordered an issue I was missing) Was that an X2 he was working with though? I seem to recall being disappointed that it was some kind of other "mini mill" and not an X2 as I was hoping for. I may have to dig that series out and re-read it. Hmmm I might even disassemble the issues to have the whole story in one place.

[Fastest1]

This guy is the 1 I have seen on YT.https://www.youtube.com/user/MuellerNick/videos
He seems very knowledgeable. Pose him a question or 2.

[Gregj888]

Troy, If not it was very close and showed the steps nicely.

[TroyO]

Gregj888, Quite true... I read that article before I did any scraping at all, I should go back and re-read it now that I've gotten my hands dirty, LOL. I bet I get more out of it now.

LOL. MuellerNick and some others have very good free videos up on youtube. I also got the video titled "Scraping For Alignment Two Disc DVD" from Ebay which was good for methods of measurement and alignment but pretty shallow on technique for the actual scraping process.

[Mcgyver]

Gregj888, Quite true... I read that article before I did any scraping at all, I should go back and re-read it now that I've gotten my hands dirty, LOL. I bet I get more out of it now.
.

Hi there,

I stumbled on this thread and am the author of that series (thanks for the kind words) and I couldn't tell you exactly what machine the castings were from! The ubiquitous mini mill. The castings appeared on kijiji. Someone had bought the parts only for a project, and wanting to include a how-to on dovetails in the series I grabbed them. Two things I can state with confidence, the parts were just bloody horrible as received, and secondly if you follow the process you can get results as nice as the nicest machine tools every made. "Nice" means the bearing surfaces are flat straight and true to one another, and that there is proper bearing over the surface area so the mechanism doesn't act like a wet noodle when under load. The sequence is well covered with enough (I hope) info so that one could puzzle out for themselves the how/why of sequencing.

With this precision scrapped x/y table in a drawer for a few years now....it begs the best the question of what to do with it. Best idea so far is a small, high speed precision cnc mill.....its something on the long to-do list

if tere

[trs]

Mcgyver, excuse me, it may be the wrong place for my questions but I can't send the private message to you.

I have seen the image of your "toolmakers cube square and parallel" in the old "Way lapping, Scraping, Gib adjustment and Lock screws" thread of this forum.

Would you be so kind as to answer the couple of my questions, please?

1)What dimensions it has?
2)Is it cast iron or steel?

Alexey