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  1. #2476
    Join Date
    Nov 2010
    Location
    Gippsland Victoria
    Posts
    733

    Default Smaller Brass Dovetail Insert : Why ?

    Quote Originally Posted by jackaroo View Post


    This is by using the sine table to cut.
    Attachment 391057
    G'day Jackaroo,

    Think I misunderstood something, see last photo, why do you need a female dovetail slot with a much smaller brass male dovetail running up the centre of it ?

    Bill

  2. #2477
    Join Date
    Jun 2007
    Location
    Vic
    Age
    48
    Posts
    544

    Default

    Hi Bill,

    That brass is the gib lying flat to show the dimples where the crews are going. Here it is with the male/female
    20210223_212817.jpg

    Regards,
    Trong

    I had another go tonight modifying the holder and I am quite pleased with it.
    20210301_210134.jpg

    20210301_211402.jpg

    20210301_211656.jpg

    20210301_211706.jpg

  3. #2478
    Join Date
    Dec 2013
    Age
    56
    Posts
    1,416

    Default

    Quote Originally Posted by jackaroo View Post
    It was on the agenda to make the sine table for a long time but I never got around it until the recent project where I needed to cut the bib for the dovetail. The “fixture” plate is removeable and I am using that on the rotary table too. Admittedly setting up the strip up is taking a bit of time as you would want the edges of the gib to be parallel, I guess I could mill a recess step for the strip to sit on.

    Attachment 391050

    Using the 8mm dowel, once the plate is bolted, I skimmed the top surface and the outer edge.
    Attachment 391051

    Setup the angle
    Attachment 391052

    Attachment 391053

    Attachment 391054

    Using the existing dovetail to support the strip makes it easier. To cut the opposite side I just elevated the strip up with the ruler and that gives the clearance required.
    Attachment 391055

    Setup to cut the second side
    Attachment 391056

    This is by using the sine table to cut.
    Attachment 391057
    I only just seen that angle plate on YouTube a few weeks ago and thought it was a great idea for the vice.

    Sent from my 5007U using Tapatalk
    Using Tapatalk

  4. #2479
    Join Date
    Aug 2019
    Location
    Revesby - Sydney Australia
    Age
    56
    Posts
    1,183

    Default Two lathe tasks

    1st was a few weeks ago. A prototype for a spray can purging tool:
    IMG_1306.jpg IMG_1307.jpg
    It also has a steel tube threaded in, which goes into the can
    (in place of the plastic spray nozzle).


    2nd was today, machining gudgeon pin sleeves for a Chevy 4:
    IMG_1361.jpg IMG_1362.jpg IMG_1363.jpg IMG_1364.jpg

    New Chevy 4 pistons are hard to find and expensive. Model T Ford is a close match, but their pins are a bit smaller, and there isn't enough material on the pistons to bore them out for the original pins.

    So the original .86" diameter gudgeon pins, which clamp in the original connecting rod little ends, get bored out to just under .74", shortened to about 1", honed, and clamped around the smaller Model T pins.

    It was a bit of a learning experience;


    • The pins are quite hard. A standard coated CCMT06 didn't last very long. A black insert (probably stainless rated?) cut better, and got me through boring two sleeves, at about 500RPM.
    • I bored the third one out too much Haven't got the hang of using telescopic gauges yet.
    • Toolmaker supplied a ceramic insert. The recommendation was to have the surface speed as high as possible, so lathe was at 2000RPM. It cut fast and beautifully (see 4th image above) while the edge held up, but...
    • ...somehow, the pin – which was held with about 30mm out of the chuck – started to wobble a little.
      (a hard spot inside might have heated/bent it somehow?)
    • ...when facing the end of the next pin, interrupted cut from wobbly end wiped it out.
    • ...somehow, the boring became less than parallel. When trying to correct that, I over-cut again.
      (I think boring with that bad insert became more of a metal-pushing operation?)
    Last edited by nigelpearson; 31st Mar 2021 at 10:13 PM. Reason: Try to add missing image attachments

  5. #2480
    Join Date
    Apr 2012
    Location
    Healesville
    Posts
    2,129

    Default

    Nigel try your ccmt inserts at 150 rpm, if you have no coolant squirt oil in the hole.
    I just bored out the centre of a very hard gear using cheap tcmt inserts at 150 rpm, it was an interupted cut through 4 gear selection dogs and once past the dogs i increased to about 300rpm, about 10 insert corners to get the job done, took me a couple of hrs to go from 30 to 45mm.

  6. #2481
    Join Date
    Sep 2008
    Location
    Riddells Creek, Vic.
    Posts
    831

    Default

    Quote Originally Posted by nigelpearson View Post


    2nd was today, machining gudgeon pin sleeves for a Chevy 4:
    IMG_1361.jpg IMG_1362.jpg IMG_1363.jpg IMG_1364.jpg

    New Chevy 4 pistons are hard to find and expensive. Model T Ford is a close match, but their pins are a bit smaller, and there isn't enough material on the pistons to bore them out for the original pins.

    So the original .86" diameter gudgeon pins, which clamp in the original connecting rod little ends, get bored out to just under .74", shortened to about 1", honed, and clamped around the smaller Model T pins.

    It was a bit of a learning experience;


    • The pins are quite hard. A standard coated CCMT06 didn't last very long. A black insert (probably stainless rated?) cut better, and got me through boring two sleeves, at about 500RPM.
    • I bored the third one out too much Haven't got the hang of using telescopic gauges yet.
    • Toolmaker supplied a ceramic insert. The recommendation was to have the surface speed as high as possible, so lathe was at 2000RPM. It cut fast and beautifully (see 4th image above) while the edge held up, but...
    • ...somehow, the pin – which was held with about 30mm out of the chuck – started to wobble a little.
      (a hard spot inside might have heated/bent it somehow?)
    • ...when facing the end of the next pin, interrupted cut from wobbly end wiped it out.
    • ...somehow, the boring became less than parallel. When trying to correct that, I over-cut again.
      (I think boring with that bad insert became more of a metal-pushing operation?)
    This sounds like a lot of unnecessary work and heartache when a simple mild steel or even 4140 bush would have done the job. Is there any specific reason for using an extremely hard gudgeon pin.

    How are you honing the I/D?

  7. #2482
    Join Date
    Aug 2019
    Location
    Revesby - Sydney Australia
    Age
    56
    Posts
    1,183

    Default

    Quote Originally Posted by Techo1 View Post
    This sounds like a lot of unnecessary work and heartache when a simple mild steel or even 4140 bush would have done the job. Is there any specific reason for using an extremely hard gudgeon pin.

    How are you honing the I/D?

    I had some 40mm dia. 4140, but turning that down to size, then machining the inside out, seemed like more work?

    (of course, I didn't know how hard they were until I started)


    The vintage engine guy honed them out with a connecting rod honing machine. Don't know the brand, probably Repco, it uses Sunnen stones.

  8. #2483
    Join Date
    Mar 2011
    Location
    Southern Flinders Ranges
    Posts
    1,536

    Default

    Opened my mouth with a counter opinion to my other half yesterday and it didn’t end well, the bright side being I got left alone in the shed for a protracted period and knocked out a couple of things from the to do list..

    Made a new base for my trim router out of a piece of IKEA cutting board, and some soft jaws for the Dawn vice I had listed in the marketplace area that hasn’t sold.
    Attached Images Attached Images

  9. #2484
    Join Date
    Aug 2019
    Location
    Revesby - Sydney Australia
    Age
    56
    Posts
    1,183

    Default

    Spent some time filling the new QCTP holders:
    IMG_1379.jpg

    and turned down the oversized head of a square bolt-head spanner:
    IMG_1380.jpg IMG_1381.jpg
    (right hand side was roughed by negative rake TNMG16 tool)


    Then, onto one of the holders, which was a poor fit from the factory. One of the Vs had a .3mm gap on one side:
    IMG_1352.jpg

    so, into the mill for some munging:
    IMG_1387.jpg IMG_1388.jpg


    I started with a blunt 8mm mill. It didn't cut well, mainly rubbing. So, tried with a blunt two flute 12mm slot mill. Started out OK, but second or third pass was groaning and vibrating. I might have been spinning too fast. Found a four flute 12mm end mill. It was also blunt, but dropping below 300rpm, and a drop of cutting fluid (tap magic), got some workable chips:
    IMG_1389.jpg


    Then, toolmaker neighbour looked in, and offered to surface grind. He didn't spend a lot of time, but it tidied up a bit:
    IMG_1390.jpg


    That got the outer V to .05mm on one end, and touching in the middle. Doesn't make the lathe tool that much more rigid - deflection on a boring bar dropped from 15 to 10thou - but it makes me happier!

    (next time I will try using the edge of these gifted blunt old milling cutters?)

  10. #2485
    Join Date
    Jan 2004
    Location
    Mackay North Qld
    Posts
    6,446

    Default

    Hi Nigel,

    If you are like myself you must really disappointed in purchasing a new tooling item that should be ready to go and then requires extensive work just to allow it to fit.

    Perhaps we can create a new definition for a quality chinese tooling product that could be:

    " A product that does not require any extra work to make it fit for its purpose."


    Grahame

  11. #2486
    Join Date
    Aug 2019
    Location
    Revesby - Sydney Australia
    Age
    56
    Posts
    1,183

    Default

    Quote Originally Posted by Grahame Collins View Post
    disappointed in purchasing a new tooling item that should be ready to go and then requires extensive work just to allow it to fit.

    A little, but most of them were good, and at $33 each?
    More disappointing was the responses when I told them it was "a loose fit":


    Can you send us the video to our email address? ...Thye tool holder is made by metal, it's solid metal, so it can't be loosen.
    "don't have a video, just that photo. It is loose because the tool holder has been made the wrong size."

    The photo can't indicate what you said. It had not shown the model of the tool holder. Can you send us a video? Frankly speaking, the block on the tool post is adjustable, you can adjust the live block to tighten or loosen the tool holder.
    The single photo can't shows all what we said, it can't help us to understand what has happened.

    And they are right, cranking the cam really tight did make it lock, but so would a 12thou shim.
    After that response I gave up trying to improve their quality assurance.


    Quote Originally Posted by Grahame Collins View Post
    Perhaps we can create a new definition for a quality chinese tooling product that could be:

    " A product that does not require any extra work to make it fit for its purpose."

    Grahame

  12. #2487
    Join Date
    Jan 2016
    Location
    Wodonga Vic
    Age
    38
    Posts
    633

    Default Water Jet

    I've been playing around with the water jet at work in the afternoon when everyone goes home, the plan is to teach myself how to use it.

    I was curious if it would cut some gears so I went to McMaster Carr website and downloaded a CAD file of a mod 2 spur gear and after a bit of trial and error I managed to cut these, one nylon, the other inconel (that's all I had on hand) they aren't perfect, I need to work on the lead in and lead outs and maybe add some tabs to hold the piece in the parent stock.

    So far I guess it's a success...?

    IMG_1334.jpg

    Does anyone here operate water jets? hopefully I can pick some brains

  13. #2488
    Join Date
    Sep 2012
    Location
    York, North Yorkshire UK
    Posts
    6,439

    Thumbs up

    Hi Ned,

    From those pictures they to to be very workable !
    Best Regards:
    Baron J.

  14. #2489
    Join Date
    Aug 2019
    Location
    Revesby - Sydney Australia
    Age
    56
    Posts
    1,183

    Default Swords to ploughshares

    A fun hour or two, machining a bush for the top of my QCTP. I used to have just a 3mm thick washer, but wanted something that located perfectly on the toolpost stud IN the tool block.

    Took a while to find some suitable steel. A cut up gun barrel, originally made in Lithgow small arms factory!
    It already had a hole in the middle, and the large end was about the right diameter:
    IMG_1475.jpg
    Stud is 18mm at the bottom, and an M16 thread at the top, so for a perfectly tight fit the inside bores had to be stepped. Hole in the tool block is 20mm ID.

    Parting off was a slight issue. Hard steel, blunt insert, and I think tool was too high. End result was very hot machined bush:
    IMG_1477.jpg

    but some finishing cuts, to fine tune the height so the toolpost locking nut/handle sits in a good position, and it looks almost professional:
    IMG_1478.jpg IMG_1479.jpg
    Attached Images Attached Images

  15. #2490
    Join Date
    Nov 2007
    Location
    melbourne australia
    Posts
    3,228

    Default

    Must have been some gun! Definitely not small arms.
    Chris

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