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  1. #61
    Join Date
    Dec 2007
    Location
    Adelaide
    Posts
    155

    Default

    Good to see you have the saddle working to your satisfaction - I know it's a little bit of a bummer when you take care to get everything machined square and then you have to pack up with shim or something similar.

    In making my Quorn I bored the spindle housing in the mill as it is an odd shape and was much easier to setup in the mill - as I approached the final size I realised that the bored hole was beginning to become tapered I was at a loss to know why but suspect that as the spindle housing was quite long (over 4inches) the quill was flexing once it was a few inches out of the mill head. The hole ended up oversize by approx 80 thou and was still tapered, I ended up setting it up in the lathe and successfully bored the taper out of it, fortunately I had not yet made the spindle so I could compensate by making the spindle OD slightly oversize to match.

    With regard to the tapping compund, I have some stuff that I can only describe as brown goop, it was mixed up by a local guy and sold through a small hardware store that has long closed due to stiff competition from our large chain hardware group Bunnings. I suspect that the basis of the compound is lard with some sort of mineral oil added to keep it soft enough to be used from sauce type squeeze bottle.

  2. #62
    Join Date
    Sep 2012
    Location
    North Yorkshire UK
    Posts
    2,332

    Talking Cutting Compounds.

    Hi Familyguy,

    Thanks for your comments.

    Quote Originally Posted by familyguy View Post
    Good to see you have the saddle working to your satisfaction - I know it's a little bit of a bummer when you take care to get everything machined square and then you have to pack up with shim or something similar.
    To be honest, I did know that the saddle plate had a problem after I had measured it and discovered that it wasn't square at both ends. Putting in the mill vise and flycutting the bad end was going to make it even shorter. I chose to take off 20 thou starting at the high end and put a shim in there. I could really do with another thou, but that can wait for a while. I need to get the top slide machined then I can get on with making the leadscrew.

    In making my Quorn I bored the spindle housing in the mill as it is an odd shape and was much easier to setup in the mill - as I approached the final size I realised that the bored hole was beginning to become tapered I was at a loss to know why but suspect that as the spindle housing was quite long (over 4inches) the quill was flexing once it was a few inches out of the mill head. The hole ended up oversize by approx 80 thou and was still tapered, I ended up setting it up in the lathe and successfully bored the taper out of it, fortunately I had not yet made the spindle so I could compensate by making the spindle OD slightly oversize to match.

    With regard to the tapping compund, I have some stuff that I can only describe as brown goop, it was mixed up by a local guy and sold through a small hardware store that has long closed due to stiff competition from our large chain hardware group Bunnings. I suspect that the basis of the compound is lard with some sort of mineral oil added to keep it soft enough to be used from sauce type squeeze bottle.
    At four inches, I would have thought that the boring bar would be flexing causing the taper. I've had a similar experience where the hole got smaller as it got deeper. 8 mm diameter boring bar, in my case, boring bars are not particularly rigid.

    With respect to shimming, I did/do expect to have to put shims in various places, but so far this is the only one.

    The two tins of cutting compound that I mentioned, Trefolex and Temaxol are both lard based with mainly sulfer and white lead added, plus other ingredients and as you mentioned a vegetable oil to adjust the consistency. These tins are both well used, being well over twenty years old, there is only about an inch in the bottom of one and not much more in the other. They are certainly a much better cutting compound than the Rocol one.

    I've found that a brushed on layer of diesel is nearly as good, particularly on aluminium, though I've used paraffin, wd40 and other concoctions with varying results. I keep coming back to the old time proved products.
    Best Regards:
    BaronJ.

  3. #63
    Join Date
    Sep 2012
    Location
    North Yorkshire UK
    Posts
    2,332

    Thumbs up Top Slide slots.

    Hi Guys,

    I've now set up to machine the slots down either side of the top slide.

    16-06-2019+001.jpg
    I used the same technique as I originally used, to ensure that the vise had not moved during the last milling session and that the work was as square to the table as I could get it.

    16-06-2019+003.jpg 16-06-2019+002.JPG
    These are the readings at each end of the work piece. A one thou difference is not going to cause any problem here. In any case that thou could be a slight twist in the plate or a difference in thickness from one end to the other. Its a pity that the very expensive Mitutoyo Gauge doesn't display tenths of a thou, only the nearest 0.5 thou.

    16-06-2019+005.jpg
    Here I am about to take the second 1 mm deep cut in the other direction.

    16-06-2019+004.jpg
    Its quite difficult to see but if you look at the right side of the slot, just above the middle of the picture, there is a chunk stuck out. The black spot to the right of that is the corner of the slot drill. The sound of cutting suddenly changed. At first I didn't realise why until I examined the cutter, and found the the corners had broken off. I did wonder if that was why the bottom of the slot in previous cuts was so rough.

    17-06-2019_004.jpg
    I replaced the slot drill with the only other 12 mm cutter that I had, a four flute Dormer end mill and set it up again to do the last pass to get to the 3.25 mm depth I wanted. I was quite surprised by the difference in smoothness of the slot. this picture was taken after I had cut the slot to the 13 mm width to suit the bearings.

    Actually the slot ended up at 3.35 mm deep and 13.1 wide with the new milling cutter.

    The next job was to clean and deburr the work before setting up to mark the hole positions for the bearing support plates that hold the top slide.

    16-06-2019+006.jpg
    These are the two side bearing support plates being checked against the saddle plate before having a pair of bearings fitted. The top slide and the saddle plate are clamped together with a 30 thou shim between them. Then the support plate is inverted with the bearings fitted into the slot. A transfer punch is then used to mark the hole positions on the saddle. The whole thing is then turned over and then same thing is done on the other side of the saddle. this ensures that the hole positions are precisely in the right spot.
    17-06-2019_002.jpg 17-06-2019_001.jpg
    This is how the sandwich of the top slide, shim and saddle plate is secured ready for marking the hole positions. Those clamps are really intended for holding wood, they are made from glass reinforced plastic and are quite easy to flex the jaws when tightening them. But that is all I have that were deep enough to hold the pieces together whilst marking the hole positions.

    17-06-2019_003.jpg
    The three items disassembled after marking the fastening hole positions. The side plates were left in place so that they could be used to locate the top slide support plates.

    17-06-2019_006.jpg
    Holes marked before the bearing side plates are removed.

    That is all for now. Drilling and tapping to be done before a test fitting.

    Thanks for looking: As always, your comments welcomed.
    Best Regards:
    BaronJ.

  4. #64
    Join Date
    Sep 2011
    Location
    Ballarat
    Age
    60
    Posts
    3,051

    Default

    Thoroughly enjoying this thread John, Great work.

    Phil

  5. #65
    Join Date
    Aug 2011
    Location
    Melbourne
    Posts
    3,966

    Default

    Same. Thanks for posting baron, it's looking great.

    Simon
    Girl, I don't wanna know about your mild-mannered alter ego or anything like that." I mean, you tell me you're, uh, super-mega-ultra-lightning babe? That's all right with me. I'm good. I'm good.

  6. #66
    Join Date
    Sep 2012
    Location
    North Yorkshire UK
    Posts
    2,332

    Default

    Hi Guys,

    Not really a lot to report today. I've got all the holes in the saddle drilled and threaded. I did have one little mishap ! I managed to break the point off the centre drill when drilling the last of the hole positions. Unfortunately it broke in the hole just at the point where the taper finishes. I couldn't get it loose no matter how hard I tried.

    By shear chance I had a 5 mm carbide printed circuit drill with a 3 mm shank that I had bought but never used. Anybody that knows, these drills have a very flat cutting point, about 160 or 165 degree angle. More like a milling cutter than a normal drill point. So I very carefully used that to drill down into the metal until I got to below the broken piece, after which I switched to a normal 5 mm drill.

    I think that I was very lucky there. The centre drill was a good quality Dormer as well, it was one that I had used many many times in the past without managing to break it. The other end is fine and completely usable.

    I've still a couple of pins to make for the bearing axles and then I can do a trial assembly before moving on to making a leadscrew.

    My thoughts on this is to go with something that is a 1.25 mm pitch like Left Hand M10 or M8, both of which I can single point on the lathe. The real question is can I successfully cut this thread over the nine or ten inches required and then can I make a nut to suit. A thread of this pitch would also provide 50 turns to the inch so I would have to scale the knob with 50 calibration marks.

    Thanks for looking and following me. Comments welcome.
    Best Regards:
    BaronJ.

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