Niels Abildgaard | 07/06/2020 20:58:43 |
470 forum posts 177 photos |
Do we have a race? I have speculated very hard for years how to make the first part of the slitting nice and today I saw the ligth. I use my very good (and rather expensive) Rest of the way will be hacksaw and is OK. |
JG | 08/06/2020 00:44:57 |
9 forum posts | Must admit, I'm excited to see the tools which are produced from this thread.. I'd quite like to give one a try but have visions of the tool bit being pushed down in the holder during a heavy cut. |
Paul Lousick | 08/06/2020 01:54:51 |
2276 forum posts 801 photos | I have one of the tangential holders made by Eccentric Engineering which cuts well and easy to sharpen and yes, the tool bit can get pushed down into the holder. But only under heavy shock loads and is more of a safety feature than a problem. Instead of re-sharpening a broken cutter, just move it back to the correct position. Paul. |
Niels Abildgaard | 08/06/2020 06:07:05 |
470 forum posts 177 photos | Posted by JG on 08/06/2020 00:44:57:
Must admit, I'm excited to see the tools which are produced from this thread.. I'd quite like to give one a try but have visions of the tool bit being pushed down in the holder during a heavy cut. My toolslip have always been a caused by brain failure. Forgetting to tigthen up after a regrind. I experimented quite a lot with different screw head forms,differential screws and worse. After making my screws like picture there have not been any slips caused by screw. M8 with 0.5mm pitch. Edited By Niels Abildgaard on 08/06/2020 06:07:55 Edited By Niels Abildgaard on 08/06/2020 06:15:02 |
DiogenesII | 08/06/2020 08:24:49 |
859 forum posts 268 photos | Good morning, I had some success measuring and milling yesterday, and some failure with surface finish.. ..unfortunately, the tedious responsibility of "work" intrudes today, I will post some photo's and a fuller text this evening
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DiogenesII | 08/06/2020 08:30:30 |
859 forum posts 268 photos | ..parting a slot - now that is scary! ..I'll stick with a slitting saw.. |
old mart | 08/06/2020 14:18:26 |
4655 forum posts 304 photos | There is a YouTube video of either Sandvik, or Kennametal demonstrating parting off a section of railway line in a lathe. Personally, I wouldn't have the nerve to try it. |
Niels Abildgaard | 08/06/2020 18:45:22 |
470 forum posts 177 photos | Posted by DiogenesII on 08/06/2020 08:30:30:
..parting a slot - now that is scary! ..I'll stick with a slitting saw..
You aint seen nothing yet It has tasted a 12.9 screw and chatters at lower work rate than my 2times 2 square versions. The distance from front bearing to work area is far to long. Bigger spindle and shorter overhang before making final verdict. Edited By Niels Abildgaard on 08/06/2020 18:47:19 |
old mart | 08/06/2020 20:29:22 |
4655 forum posts 304 photos | Makes me glad to have the use of two mills, although not while the lockdown stops the museum from opening. |
DiogenesII | 08/06/2020 22:56:08 |
859 forum posts 268 photos | Bah - 9 humid hours of clipping Buxus Sempervirens, followed by the infuriating agony of "Microsoft Photos" mysteriously re-materialising on my PC and sending two years worth of pictures that MS didn't know I had back to Silicon Valley, presumably to be inspected for any identifiable brand logos and the faces of people who might be on my contact list.. Wish you joy with that.. So where were we? ..I used Niels' method of turning a cylinder of known radius and a feeler gauge to establish that the surface of the Hobbymat slide is 10.07mm (THAT much wear, eh?..) below centre-height - milling the toolholder to this height, so that the point of the toolbit can now be set by turning the holder upside-down on a flat surface.. I think I will accept Niels' challenge and make a dedicated holder to fit the Myford - I'm sure that I will not win a straight race, but maybe I can cheat, or think of an even more outlandish set-up. I really need to get some new toolbits ordered - the small HSS drill-shanks are coming to an end, and because most have been used/chewed, I notice that although the overall surface finish is okay, using magnification shows that "Edison Phonograph Cylinder" effect.. Stoning, testing & stoning "old" 2mm rounds is one of those things that life may be too short to be doing much of.. I'll have to sell my television or something, and buy a 2 x 100mm stick of carbide. And a quality pin vice, maybe.. How and what do you sharpen your toolbits on, Niels?.. What a day..
Edited By DiogenesII on 08/06/2020 22:58:57 |
Niels Abildgaard | 09/06/2020 06:49:35 |
470 forum posts 177 photos | Posted by DiogenesII on 08/06/2020 22:56:08:
How and what do you sharpen your toolbits on, Niels?..
Edited By DiogenesII on 08/06/2020 22:58:57 There is a picture of sharpening here and stone is a carborundum or silizium carbide and not expensive,but diamond in some form is better. |
Jouke van der Veen | 09/06/2020 10:30:42 |
203 forum posts 19 photos | Posted by Niels Abildgaard on 07/06/2020 10:40:18:
Concerning round tangential toolbits. It was tried with 3,4 and 6mm round carbide and flat top on mild steel. It worked very well until depth of cut was equal to radius of toolbit ,that is 1.5 and 2 and 3mm. The cutting edge was much more robust than any of my homebrewed square things. Interupted cuts,cast iron skin etc For our small lathes there is no reason to opt for bigger toolbits as 1 to 2mm depth of cut is power limit anyway
Niels, Could you explain why the depth of the cut can not be deeper than appr. the radius of the toolbit? I expect that you mean that cutting a depth of, lets say 2mm, will be done in more steps. I intended to use some kind of tangential tool holder to cut a radius in a home made milling cutter for clock wheels. For this I have to go deeper than the toolbit radius. When you start with a toolbit with known diameter and you place it in a holder under a known angle to the vertical then the small radius of the horizontal elliptical cross section of the toolbit is exactly defined. Of course, this radius is not constant moving along the circumference of the ellips but it varies only a bit for a substantial angle. Regards, Jouke
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Jouke van der Veen | 09/06/2020 10:30:43 |
203 forum posts 19 photos | was double
Edited By Jouke van der Veen on 09/06/2020 10:39:29 Edited By Jouke van der Veen on 09/06/2020 10:40:04 Edited By Jouke van der Veen on 09/06/2020 10:40:30 |
Jouke van der Veen | 09/06/2020 11:13:11 |
203 forum posts 19 photos | This was the “trial” tangential cutter I used. A toolbit of silver steel in a brass tool holder. Angle of toolbit and diameter were chosen to get the desired cutting radius. I used it in an Emco Compact 5. Edited By Jouke van der Veen on 09/06/2020 11:14:03 |
Niels Abildgaard | 09/06/2020 11:59:45 |
470 forum posts 177 photos | Niels, Could you explain why the depth of the cut can not be deeper than appr. the radius of the toolbit? I expect that you mean that cutting a depth of, lets say 2mm, will be done in more steps.
There is an old thread that have pictures etc. I tried 6mm carbide and allwent well untill 2.5mm depth of cut.Then lathe was not really up for more.It was therefore reasonable that a 3mm tool should be able to do 2.5mm wide also from a lathe power viewpoint. That might have been the case put cutting was not possible.Noise was unpleasant,swarf curled wrong and it had to stop. Doing 1.5mm and down it was pure music
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Leo F Byrne 1 | 09/06/2020 13:29:28 |
15 forum posts | I have a tangential tool holder from Eccentric. Wouldn’t be without it. |
Niels Abildgaard | 09/06/2020 13:47:13 |
470 forum posts 177 photos | Posted by Leo F Byrne 1 on 09/06/2020 13:29:28:
I have a tangential tool holder from Eccentric. Wouldn’t be without it.
What lathe do You have? It could be fun if someone will try and compare with my homemade.
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Niels Abildgaard | 09/06/2020 15:03:08 |
470 forum posts 177 photos | Posted by Jouke van der Veen on 09/06/2020 11:13:11:
This was the “trial” tangential cutter I used. A toolbit of silver steel in a brass tool holder. Angle of toolbit and diameter were chosen to get the desired cutting radius. I used it in an Emco Compact 5. Edited By Jouke van der Veen on 09/06/2020 11:14:03 Jouke Interesting,but why so much tilt on toolbit if You can make it to any diameter,as I asume You can from the photo? Your Emco spindle has what I ,after much consideration and not much expirience, consider the best way. Three or four screws through chuks to front of spindle. Very short ,strong,safe and fast to change.Whats not to like? |
Jouke van der Veen | 09/06/2020 16:43:45 |
203 forum posts 19 photos | The toolbit + holder shown in the picture have the following dimensions (I just measured): Diameter at top: 4.5mm Angle from vertical: 26 degrees These values together define a defined minimum radius of the horizontal ellips at the tip of the toolbit. I have to calculate it again to achieve the required radius I wanted some years ago. So, by choosing a combination of diameter and angle you make a required tip radius in the horizontal plane. You set the top of the toolbit at center height to cut the required radius I tried to use this tool to cut a radius in the corners of a disc blank. The first step in making a milling cutter. The problem was that it did not cut so well and I stopt wit it. A different approach would be to braze a carbide ball with a diameter more than 2x larger than the required radius on the tip of steel toolbit and then grind the ball down to below center to the height with the required radius. |
DiogenesII | 09/06/2020 20:02:11 |
859 forum posts 268 photos | Posted by Niels Abildgaard on 09/06/2020 06:49:35:
Posted by DiogenesII on 08/06/2020 22:56:08:
How and what do you sharpen your toolbits on, Niels?.. There is a picture of sharpening here and stone is a carborundum or silizium carbide and not expensive,but diamond in some form is better. Thanks for that, it is much as I thought, except that on Sunday I hadn't thought of, er, the high-level advanced technique of using a strip of abrasive paper And still I can't find a day to make chips. Work is the curse of the Model Engineering classes.. |
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