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  1. #466
    Join Date
    Sep 2012
    Location
    York, North Yorkshire UK
    Posts
    5,402

    Thumbs up Modified 6 mm Drill.

    Hi Guys,

    Thank you for looking at my modified Brooks TCG ! I said that I was going to do some grinding with it and I admit not getting on with doing the job. Anyway today I had a need to modify a 6 mm drill in order to enlarge a 3.5 mm diameter hole that had been cast off centre in a broken off, cast brass spigot.

    Since the existing hole was a couple of mm off centre I couldn't just use a normal drill and drill it out, it was a boring bar job, but I don't have a boring bar that small ! So I resorted to re-grinding a 6 mm drill into a "D" bit cutter. This is where the Brooks grinder came in !

    Unfortunately I was so engrossed in setting up and grinding the drill, I didn't take any pictures of the setting up and grinding the drill. Sorry about that ! A case of learning on the job .

    18-08-2021-004.JPG 18-08-2021-003.JPG

    I did however take these pictures of the drill after I had ground the end and used it to bore a 1/4" hole through the brass spigot.

    As far as setting up the Brooks grinder to do this job, it was a matter of using the right size collet and getting the drill bit angled to grind the face. I set the horizontal angle at about 7 degrees anticlockwise and set the drill horizontal with respect to the centre of the wheel but above centre by approximately twice the drill diameter. This gave me the angles that you see in the pictures.

    18-08-2021-001.JPG 18-08-2021-002.JPG

    Here you can see the brass spigot in the lathe chuck and the fine swarf that the machining produced. The drill cut very easily with no tendency to pull into the work. I ended up with a good fitting 1/4" inch diameter hole.

    This is just for a small collar to act as a stop on a length of 1/4" inch steel rod. I've yet to drill and tap for an M4 grubscrew through the side and part off to length.

    Thanks all for looking !
    Best Regards:
    Baron J.

  2. #467
    Join Date
    Sep 2012
    Location
    York, North Yorkshire UK
    Posts
    5,402

    Thumbs up Lathe tool Holder !

    Hi Guys,

    Its been quite a while since I've added anything to this thread, other things have taken presidence in the work order. Because of a new project I need to grind a special lathe tool, very similar to a threading tool but with a 40 degree included angle.

    In order to grind lathe tools, I need to make a holder that I can use on the modified Brooks grinder to hold them. I can adjust the existing holder to obtain all the angles that I need but that only hold round tools like milling cutters and drills.

    Below is a drawing of the tool holder that I am going to make that will fit in place of the existing tool holder.

    Lathe tool holder.png

    The drawing shows the front and end view of the holder. I'm using a scrap bit of 1 inch square black CRS, squared up and the holes drilled and threaded to clamp the lathe tool bit. The 6 mm diameter countersunk hole in the middle is basically the pivot point. I'm also using M6 screws to hold and clamp the lathe tool whilst grinding it. The small 4 mm counter bored holes are for the two M4 cap screws that will be used to fasten the holder to the rotatable plate, allowing for angle adjustment. I will take some pictures of that later.

    Thanks all for your support its much appreciated.
    Best Regards:
    Baron J.

  3. #468
    Join Date
    Sep 2012
    Location
    York, North Yorkshire UK
    Posts
    5,402

    Thumbs up Lathe tool holder finished !

    Hi Guys,

    I've spent Yesterday and most of today milling and drilling the block for the lathe tool holder to fit onto the Modified Brooks TCG.

    21-05-2022-001.jpg

    I spent some time squaring up the sides of the bit of 1" inch black CRS bar and getting it to 25 mm square, not that it was too critical ! But its nice to have a clean piece of sized material to play with. Notice the stop on the left side in the next picture. Since I'm going to rotate the workpiece to drill the clamping screw holes, I need to be able to maintain my edge reference.

    21-05-2022-002.JPG

    In this picture I'm drilling the three main holes. I used the half function on the mill DRO to get the centre line for drilling. The two outer holes are drilled for M4 clearance and the middle one drilled for M6 clearance.

    21-05-2022-003.JPG

    The next step was to drill a 12 mm diameter hole 13 mm deep ! This step is important because I'm going to use an M6 countersink screw to secure this part to the bracket that will support this lathe tool holder and allow it to swivel in order to be able to adjust the angle.

    21-05-2022-004.jpg

    This is the holder after I have milled it out for a 1/2" wide slot. You can now see where the countersink has been formed by the 12 mm drill. I used a 12 mm four flute milling cutter at 1000 rpm, taking baby 1 mm deep cuts, as can be seen by the swarf on the rear right hand edge of the workpiece to machine the slot.

    21-05-2022-006.JPG 21-05-2022-005.jpg 21-05-2022-007.jpg

    Here I am trying a piece of 1/2" inch HSS tool steel in the slot to check the fit and make sure that the M6 CSK screw has some clearance. I don't want the lathe tool to rock on the screw head. At this point I have not counter bored the 4 mm holes for the M4 cap screw heads. I did this later by putting it back into the mill vice and using the DRO numbers.

    21-05-2022-008.JPG

    This is the holder after the M4 screw holes have been counter bored. They are counter border to a depth of 4.5 mm, enough to give them a little clearance under any tool held in the slot.

    21-05-2022-009.JPG

    Although the drawing shows two M6 clamp screw holes, since I already had the numbers from drilling the M4 holes, I decided to put in a third hole. These holes were drilled 5 mm and threaded M6 for clamping screws.

    More to come. The fittings on the Modified Brooks TCG are up next.

    Thanks for looking guys, your support is much appreciated.
    Best Regards:
    Baron J.

  4. #469
    Join Date
    Dec 2007
    Location
    Adelaide
    Posts
    443

    Default

    Seems like it is never ending with these diy projects there is always an extra attachment to make - looks like good work. The first HSS holder I made fitted into the 16mm ER chuck collet, it worked ok until I needed to grind a 1/2" HSS tool, so I made another that replaced the ER collet chuck a 1" bar with a 1/2" square hole through the middle.

  5. #470
    Join Date
    Sep 2012
    Location
    York, North Yorkshire UK
    Posts
    5,402

    Thumbs up Tool holder set up !

    Hi Guys,

    As promised these are a few pictures of the new lathe tool holder set up on the modified Brooks TCG.

    22-05-2022-003.jpg 22-05-2022-004.jpg

    These two pictures show the modification to the existing spare pieces of 6 mm thick plate. Actually a second spare swivelling plate as used to support the original work holder. I simply cut the piece at the top off and drilled a 6 mm diameter hole 12 mm up from the cut off piece.

    Then using the rotary table on the mill, I then extended the existing curved slot to suit the new hole as the centre. You can see that because the new radius is smaller than it was originally, the slot extends beyond the original one. After doing this I used a cap screw to clamp both pieces together and then drilled and tapped a hole in the backplate to suit the curved slot. The bright screw ends that you can see in the second picture are the M4 fastening screws holding the new lathe tool holder to the moveable plate.

    22-05-2022-001.jpg 22-05-2022-002.jpg

    These pictures show the new lathe tool holder fastened to the movable plate and the screws securing it to the back plate and also the M6 clamping screw with the washer on it. This gives me just a fraction under 40 degrees of tilt in either direction.

    22-05-2022-005.jpg 22-05-2022-006.jpg 22-05-2022-007.jpg

    This first picture shows the backplate mounted on the grinder and clamped in place by the two M6 grub screws, note that the back plate can be turned around and secured with the grub screws. As shown the backplate can hit the back of the motor. It also shows how the lathe tool can be tilted to suit the working angle required. The middle picture shows how the work holder can be angled to obtain approximately 20 degrees either way.

    Whilst the lathe tool holder is designed to hold a 1/2" inch HSS tool blank, some packing is needed in order to securely hold a 4 mm square HSS tool blank. That is a 6 mm piece of square HSS under the 4 mm HSS tool blank. In the last picture there is a 3 mm thick plastic spacer, used in order to push the smaller HSS tool blanks away from the back and allow the fastening grub screws to rest on the middle of the HSS tool blank.

    At this point the work on the lathe tool holder is finished ! All that remains now is to grind a suitable tool bit for cutting the multi "V" belt grooves.

    Thanks guys for your support. I'll add to this thread as necessary in the course of grinding my required lathe tool.
    Best Regards:
    Baron J.

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