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Thread: Metrology For the Cabinermaker - II

  1. #16
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    Your posts are always interesting Brian! I’ll have to check my DM a little closer when I get home. For door work it’s accurate enough but can see your quest for furniture making.
    did they re- machine the back fence? Mine is planed with deep ridges that help keep the workpiece from wanting to pull up when chisel is retracted. Would hate to loose this.

    Can you recommend a good magnetic indicator base? I want to upgrade mine. I see the Mitutoyo digital indicator. Do you prefer that to the dial type?

  2. #17
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    Thanks, Joe! Loosing the grooves was the lesser of two evils. Option B was to re-grind the table ways parallel and square to the fence which required scraping in the saddle. Being that the ways were accurate I hated to do that.

    I am looking at ways to reapply the grooves, currently. I plan to do so when I drill for holes to locate the mini-pallet.

    Fisso is a really nice Swiss made indicator base. Probably as good as it gets.

    In the middle range I would consider Mitutoyo.

    I don’t mind dial or digital, for an indicator in fact dial is sometimes better. I like Mitutoyo Japan made but plenty of guys prefer Mahr which are made in Germany.
    Bumbling forward into the unknown.

  3. #18
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    Re: the indicator mag base. Im partial to Noga or like, and prefer dial to digital.

  4. #19
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    Thanks for the info guys.
    Very helpful

  5. #20
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    Dialing in the chisel holder was surprisingly difficult. I did not expect perfect alignment but I was surprised at the reasons why it was out.

    There are many reasons for wanting this square, primarily I do not want the chisel to deflect under load, approaching the piece with the chisel cocked is going to apply a horizontal force to the chisel, bending it.

    I checked the pin for straightness on my surface plate.

    At first glance it appears that the chisel holder is bolted up tight, but further inspection provided that one could see light between the mating parts. I decided to indicate it first to see where I stood.

    I work to set everything in alignment to travel, which is why I first make the effort to set the column square to the base's dovetails utilizing the travel of the head as my basis. That allows us to align parts to travel, rather than to each other. In theory, the limit of accuracy would be the machine ways themselves.

    First step was to chamfer all holes and deburr the surfaces at hand. There were some pretty offensive burrs, but they were easily removed with a hand burring tool and a light india stone.



    Next, I started to dig in. First thing I found was a sleeve in the bottom of the motor that was proud of the surface by quite a bit.



    I filed that back and expected the parts to mate, but they did not still. So I got some marking compound and applied it to the motor.

    At this point I also decided to indicate the spindle to make sure it was actually aligned with the ways. Normally I would use a test indicator here instead of this dumb approach, but it worked and saved me from driving to pickup my test indicator.



    This was followed by a sweep around the mating surface. I found this pretty decent, a thousandth showing here and there.



    Next, returning to the part to take a print. I came to find that the step was actually mating with the spindle bearing and preventing the part from seating. I can't imagine this was intentional. I spent some time cutting this by hand to the point where the part contacted the bearing lightly when bolted up and contacting the mating surface well.

    This resolved the issue and it checked mainly square afterward.



    Bumbling forward into the unknown.

  6. #21
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    Brian, Your home planet called and said that you have blown your cover and must return immediately.

  7. #22
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    Hah! Thanks, Mark.

    It is revealing when you start digging into parts, I found a nice big curve in the rack (and pinion) so I plan to resolve that before putting it back on the machine. I’m assuming it was deflecting the table at least a little bit.

    This process reminds me of ‘engine blueprinting’ which was the process of bringing a motor from how it actually leaves the factory into an ideal spec and how it should alter performance. I haven’t cut a mortise after having the table done and attending to these few problems but I expect it will be slightly easier than before. Quite frankly it worked beautifully even as I first received it so I’m solving very minor issues.
    Bumbling forward into the unknown.

  8. #23
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    Quote Originally Posted by Mark Hennebury View Post
    Brian, Your home planet called and said that you have blown your cover and must return immediately.
    --

    The most expensive tool is the one you buy "cheaply" and often...

  9. #24
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    Sponge Bob is from Bikini Atoll, known in his fictional world as 'Bikini Bottom'.
    Bumbling forward into the unknown.

  10. #25
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    True dat!!!!!!!
    --

    The most expensive tool is the one you buy "cheaply" and often...

  11. #26
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    Checking my DM the fence is out of square to the base by quite a bit. Almost 1mm in the height of the back fence. I do not see this as a problem as the clamp pushes the workpiece agains the back fence. I did check to see if the chisel is parallel to the back fence and it’s out about 0.3mm in the height of the fence. ( I’m sure my measuring technology is not as accurate as yours)

    I would like to correct this and thinking it might be in the chisel holder. I had 2 originals with the machine that were cracked in the bolt area but still functional. I ordered a replacement from AMS but I thought the fit was poor and the finish rough. I’ll put one of the originals back and see what that does.

  12. #27
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    Iíd be curious to see if your chisel holders also gap between the mating surfaces. I assume this is why the originals cracked. Your mention of that situation is actually what caused me to dig in here, when I bolted it up it didnít seat as it normally should and so I wanted to find out why.

    If you put some gear marking compound on the top ring I would bet that the ring contacts the bearing. I would imagine this to be a common error in these machines of a similar vintage.
    Bumbling forward into the unknown.

  13. #28
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    I’ll check the flatness tomorrow Brian. I think the holder may have cracked from wrenching the holding bolt too tight or undersize chisel. Machine originally came from a school shop so who knows. The one on the machine had a unsightly support added. I may clean it up and use it.
    64A6AEC3-E9A1-494C-8F52-1380E7E82385.jpg

    I was way off base when I checked fence squareness last night. Under better light and a rested brain it is only 0.3 mm off which would correspond to the chisel being off. I chopped a mortise today and cut it in half. It’s only 0.1 mm off parallel in 3”. I can live with that. Especially given chisel mortising is fairly crude.

    Also, I was looking at my table sideways stop rods that are original to my machine. They have a flat on the bottom and were held by square head bolts that made adjustments unhandy. I think they were BSW thread so I drilled them slightly bigger and put metric kip levers in. I noticed yours are round and must be aftermarket.

    A2AC71BE-AF8C-4B13-8875-B9939BB291A8.jpg
    Last edited by Joe Calhoon; 10-22-2019 at 6:52 AM.

  14. #29
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    Be interesting to see one of the hollow chisel mortisers from Japan that Chris talked about. I bet they are nice.

  15. #30
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    I linked you to a post of someone using a Japanese HCM. They’re actually very similar to the DM in my opinion.

    My table rods were missing so the ones in the machine now are from McMaster, they are also flat on the bottom but I didn’t replace the bolts with kip levers yet. I may do that pretty soon, I’m sure wrenching will get old quickly.

    Did the original supports have a washer in the split to limit how far the split would close? Mine does and it just barely grips tight, I used a spacer for some chisels and it added enough slack that they would not tighten and required me to swap bushings. I ended up buying another set of chisels so that they all have the same shank.

    I added a 5/8” chisel which Axminster lists as .500” shank, but I’m suspicious of that number and hoping it is larger than .500” so I can have it cut down to size.

    .004” (.1mm) is fine for most mortises I would imagine, in fact that is smaller than PVA’s gap tolerance of .005” so it should be perfectly alright. My machine produced a similar result. My reason for doing most of this is more about making certain that they chisel force is all going straight down. To me it seemed like the machine needed a tad more force than necessary to cut with the 1/2” chisel and having both parts very slightly out of alignment would certainly cause that.
    Bumbling forward into the unknown.

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