Rescraping Aciera F3 milling machine
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  1. #1
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    Default Rescraping Aciera F3 milling machine

    Hi,
    i am an engineering student from germany and i would like to get your opinion about my scraping project. I am fairly new to the topic of scraping but i read and watched alot about it. Last year i managed to scrape my lathe slides with (in my opinion) good results. Now i am planning to rescrape my newly aquired milling machine: an Aciera F3 from 1964. A fairly small machine
    (X 300mm/12inch; Y 135mm/5 inch; Z 250mm/10 inch).
    img_20190826_185821.jpgimg_20190826_185733.jpgimg_20190826_185622.jpg

    I am confident about getting a dovetail way straight and fitting the gib correctly but i wonder how to align everything to be perpendicular in the end (with few tools and without tipping the machine over).
    I only have a surface plate, straight edge and a master square which i am currently scraping in.
    My plan is the following:
    1. Scraping the Z-Axis straight. As i can´t tip the machine i have to scrape it in place. Therfore i don´t want to have to align it to anything to make the job as easy as possible.
    my biggest concern is twist between the two flats and how to measure it. My rather crude idea was to make an indicator base that registers in the dovetail and rides along the axis while pressing it onto the way.
    2019-08-26-20_25_07-praesentation1-powerpoint.jpg
    This is far from ideal but i don´t see any other way. Maybe you have a better idea.
    2. Scraping the matching Z- Slide which also connects to the X-Axis. This should be fairly simple. perpendicularity between x and z lies in this part. Should be easily measured with the master square on the surface plate.
    3. scraping the X-Axis. Should also be easy as i can measure on the surface plate.
    4. Now assamble z and x again and scrape/adjust the mounting flange of the table to be parallel to X and perpendicular to Z, by placing the Square on the table and traversing Z with an indicator running on the square.
    5. Scraping the machine side of the Y- axis flat and parallel. My surface plate is rather small (400x600mm; 16x24 inch) so maybe i can place that onto the ways upside down ? If not doing a similar thing as in 1. with the indicator base to measure twist.
    A king way like thing won´t work as i don´t have a reliable reference nor a precision level (?). Perpendicularity to Z and X again by measuring against the square on the table.
    6. Matching the Y slide while checking it on the surface plate for perpendicularity of the spindle by spinning an indicator in the spindle:
    2019-08-26-20_28_07-praesentation1-powerpoint.jpg
    7.????
    8. Profit . Or at least a reasonably straight and perpendicular machine.

    So what do you think about this plan? Realistic or not? I am glad for any advice or critizism.
    (if any more pictures are needed just say so, i could only upload 5 here (without uploading them elsewhere))

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    There are a few of us who can help you. If you look at the top of this section and look for "Stickey: and go down the list and look for Studer grinder. You will see Ballen who is German and is sharp on scraping. Also I teach scraping and have taught classes in Germany and will be teaching 3 classes in Austria in October. The classes will be held inside a professional machine rebuilders shop too. The classes are being sponsored by BIAX. Also Jan S in You tube shows on rebiuilding machines can help he has several . YouTube Scraping Class 2019 with Richard King - BIAX

    When you rebuild a fixed spindle machine start there and get all your geometries. Also remember to calculate sag. Pic's are from classes I taught in Germany and Austria.
    Attached Thumbnails Attached Thumbnails maschratur-71-_2-1-1-.jpg   20181113_095739.jpg   img-20171207-wa0000.jpg   dsc02979.jpg   dsc02980.jpg  


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    Thanks for the kind words Richard. I have no doubts that one of your scraping classes would be higly beneficial for learning. However as a student i can´t really afford it right now. Also i love learning for myself and jumping into big projects (without the skills/knowledge needed)always gave me a lot of headaches but in the end a greater sense of accomplishment and lessons learned.
    Maybe you can solve my biggest problem: How to measure twist in a vertical machine way?

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    Feynman,
    Just two quick comments.
    Precision level vials are relatively inexpensive (< $100) and extremely useful. Something I strongly suggest you add to your toolbox.
    To measure the twist you need two blocks to rest a parallel on top and a dial indicator: you place the blocks on the opposite ends of the ways and the parallel on top of them (i.e. diagonally across the ways), indicating in the middle. You repeat the measurement on the other diagonal, without moving the dial indicator: if the ways are twisted, the two measurements will be different.
    If you are smart enough, it won't take you long to realize that the parallel and blocks could be replaced by a rigid enough bar/weldment with three flat spots: two at the ends, coplanar (you definitely need no rocking, when resting on your ways), and one in the middle of the opposite side, parallel to the other two (the area where you indicate with your dial indicator).

    Paolo

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    Giving some visual to Paolos post.
    Theres a video on Robins instagram showing his take on the two foot gauge. Super simple and very accurate.
    Robin Renzetti on Instagram: Two foot twist gage
    Cheers D

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    Be sure you keep the blocks solid , Check out how we made an easy bolt together fixture
    YouTube

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    Ah the twist gage . I feel kinda stupid now as i read foundations of mechanical accuracy a few months ago and only now remember this measuring technique. This should sort out most of my problems. On friday i have my last exam (for a while) and will start scraping then.

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    Quote Originally Posted by feynman View Post
    I am an engineering student from Germany
    I have taken Richard's class and done some simple scraping work, so might be able to help. Where are you located? Write to me privately if you don't want to advertise your location.

    Cheers,
    Bruce

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    thanks for the offer, i am located near Mannheim. Right now i feel pretty confident about the project. But it would be nice to be able to get help if i hit a roadblock.

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    I would you suggest you either look for a new machine spec sheet that came with the machine or search the Internet for the Germany book "Testing Machine Tools" written by DR. George Schleshinger. When I taught a class in Stuttgart one of the students had a copy written in German.

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    Thanks for the tip Richard, my university library actually has it. I will get it when i am back at university. Full name in german is "Georg Schlesinger: Prüfbuch für werkzeugmaschinen".

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    So quick update, got the bandsaw tabl... ehhm Master square scraped in. Scraping professionals should probably look away now . I first "step ground" the square to be parallel and sqare to within 0.1mm as it was out more than 0.4mm.

    img_20190831_211528.jpgimg_20190831_150836.jpg
    I then scraped two sides parallel and then kept scraping and measuring the third side to be rectangular. This was the first time using the "Biax" for me and i was fairly pleased.
    img_20190831_211645.jpg
    To me it was actually more useful for medium and finish scraping, as i feel i can take a much heavier cut by hand when roughing.
    I got really carried away with this thing and ended up scraping for 6 hours. I managed to get it within 2-4 micron parallelism (measured with a scraping puck) and measured less than 2 micron deviation for the squareness (at 250mm height). The Square is about 350x350mm (14 inches). This is way more acurate than what i need for the mill but i guess i had to prove it to myself. Quick tip for the budget oriented Scraper: These carbide woodturning inserts from china work pretty well for scraping. The backside is already lapped(maybe about 1500 grit) and you can turn the insert 4 times before resharpening(and its only 1-2 $).
    img_20190831_211720.jpg
    Attached Thumbnails Attached Thumbnails img_20190831_163820.jpg  
    Last edited by feynman; 09-01-2019 at 06:51 AM.

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    im only seeing the first pic, the rest have a no entry icon.

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    Quote Originally Posted by feynman View Post
    So quick update, got the bandsaw table... ehhm Master square
    I can also only see the first photo. Rather than hosting the photos on Google as you are now doing, it will probably work better to upload them to an album here, and then link to those from your posts. I'd like to see the photos of your carbide scrapers.

    The "blade slot" in the bandsaw table means that one side will flex quite a bit relative to the other. Did you fill it with epoxy or find some other way to constraint it? Otherwise you might consider bandsawing in into an L shape to eliminate the flex.

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    I reuploaded the photos, hope it is visible now. To be hones i am not a big fan of the photo functionality of this forum but maybe that´s just me.
    To the problem of flex: I thought the same thing and there is actually a M10 thread right through the slot, where i put in a screw. however, this had no big measurable inpact (<2 micron) except when tightened the screw a lot which flexed the casting apart i guess. I will do some more measurements on that to be sure.

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    That scraping belongs over on the hobby forum

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    Lol to the 'Biax' , and kudos to having the stones to use a grinder to rough out .
    How are you sharpening your carbide btw? 150mm lapping disks are cheap as chips on ebay, work well enough on a bench grinder. For hand scrapers you might want to make a few shanks out of 30mm x 3mm ish bright flat and braze a bunch of tips on the ends, can make any size/shape you might need and can touch them up joblot style, no messing with cap screws.
    The scraping doesnt look to bad to me, its hitting pretty well which is the main thing, a little lite on the edges but onwards and upwards, everyone starts somewhere eh.

    Cheers D

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    Thanks Demon, i actually got the idea for the power scraper from thunderDog (youtube) who made a nice video about it. I have not used a real biax for comparison but i imagine mine works at least decently. Stroke is variable from 0 - 30mm, speed is also adjustable. The chines sharpening discs you mentioned work very well, i got a set of these with 600,1500,3000 grit and also sharpen my lathe tooling with it (slow grinder 600 rpm).
    I did make two brazed scraper blades which i used for hand scraping, especially in dovetails. But for straigt surfaces i do like the insert alot. The picture of the scraping is not the finished scraping as i could not properly photograph it later when spotted lightly.

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    Quote Originally Posted by Richard King View Post
    That scraping belongs over on the hobby forum
    Yes, i do consider myself a hobbyist. Actually i have never worked a day in my life as a machinist.

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    Hi, i wanted to give a quick update about the project. It went pretty well in the beginning: I made new scraping blades for the hand and power scraper for roughing as the insert blade i showed last time has a too small radius for heavy roughing.
    img_20190909_145321.jpg
    (Same geometry for power and hand scraper)
    They did cut quite well and i managed to scrape in the straight edge.
    img_20190904_122440.jpg
    This was once a cast iron table leg which i milled down on the milling machine. (not fun milling a 800mm straight edge with 300mm of travel on a worn out machine). With the straight edge i scraped the vertical ways flat and checked the two flat sides for twist as described in my first post.
    img_20190905_100352.jpg img_20190905_100428.jpg
    The base of the gauge is a piece of mild steel which i scraped flat a long time ago as a practice piece. First i only wanted to use this as a rough estimate as it is not the ideal way to measure twist(i guess) but the measurement seemed reliable enough for the accuracy i wanted to achieve. The Z-Slide was scraped flat on the surface plate and i then used it to check if the Z-Ways were in the same plane (blued up the Z Slide and printed on the ways). Then rescrape/adjust the ways until i got good bearing.
    img_20190904_183545.jpg
    So far so good but disaster was about to strike . I tried to scrape in the last side of the Z dovetail to be parallel to the other side (measured with two dowel pins over the dovetails). I can post pictures of this measurement tomorrow if needed. The problem: this measurement showed the sides to be convex, however the blueing on the dovetail showed it to be concave . I then changed the measuring setup a number of times to come up with the same diagnosis. Finally i checked the straight edge to find out it moved over the weekend to be concave.... So now i scraped it flat again with a lot of ringing in between scraping(only did it once the first time after milling). I started to fix the Z ways today, looking good so far.


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