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22nd Jun 2021, 01:30 PM #76
pic
The last pic with the dial indicator , the larger diameter looks to be a reasonably good finish for hot rolled . The brazed carbide tool you are using is not the ideal setup for a learner , it is probably the worst out of the three choices , HSS, carbide insert or brazed carbide. I would get rid of it . I think you would be far better off with a sharp HSS tool or a Aluminium style carbide insert with a sharp edge .
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23rd Jun 2021, 01:22 AM #77China
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I have only just looked at this thread, I had the same problem when I bought my metal lathe over 20 yrs ago, I went through or same hair pulling, turned out to be a roll pin that locks the tool holder. the pin was slightly too small
allowing the tool holder to move when in use, I replaced it with a tight fitting pin and the problem disappeared, have you checked that nothing is moving it is surprising what a very tiny movement can cause.
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23rd Jun 2021, 01:40 AM #78Member
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I'll go over it tomorrow and see what moving slightly
I have noticed that the tool gets pushed back a little sometimes, but that's from the slack in the cross slide i believe ?
edit:
got these to try out as well
I got these today. Going to have a play around some HSS blanks in a couple of sizes
a right handed carbide holder with the blade things to go in
and a few of the brazed carbide tipped ones.
Also a little finishing stone for HSS and a steel shimming plate.
I have a 2mm, 3mm and 4mm shimming plate along with various feeler gauge pieces to help where needed.
199800735_1252972778495824_1838547676655015392_n.jpg
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23rd Jun 2021, 08:35 PM #79Senior Member
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You can't
I was using some degreaser spray as cutting fluid
no idea how to get rid of these marks that are still present.
First of all, that steel looks pretty horrible for turning. Some steels are like that, including a lot of bolts. Might be good for something else. Get some free machining steel and see how that goes. Really.
Check the tightness of the whole saddle: it looks as though it can wobble and let the tool dig in. If the saddle is too light, then you may not be able to prevent to prevent the wobble or chatter which gives those marks. That is a function of the lathe, and small old lathes are often looser than big new ones.
If you must use that steel, you will need a sharp cow-mouth HSS tip (ie round), a high speed and a very fine cut - both in depth and feed.
The path to learning is long.
Cheers
Roger
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23rd Jun 2021, 09:39 PM #80Most Valued Member
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If you decide to buy carbide, get positive rake tooling. I use CCMT and DCMT. I generally use a .4mm radius insert but I do keep .2mm radius inserts.
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23rd Jun 2021, 10:48 PM #81Member
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here's the latest all put together in a video
https://www.youtube.com/watch?v=6Byn8lK-rvk
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23rd Jun 2021, 11:44 PM #82Most Valued Member
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The hole in the tool holder should be a neater fit.
The tool holder should be one piece not two as shown, you really should replace the 4 way.
Has the compound always been loose as shown before you tightened it?
Are there 2 small pins at the bottom of the holes that the screws on your crosslide screw into to hold the compound?
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24th Jun 2021, 12:13 AM #83Most Valued Member
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Yeah, sort out your slide and tool post before you start heading in any other direction.
Mal at Australian Metalwork Hobbyist has spares and changeover bits, although I’d be tempted to look at a chinesium AXA (250-110/111) size quick change if you have budget for it.
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24th Jun 2021, 12:22 AM #84
Hi Mathu,
Thanks for the video ! I noticed several things. First that tool holder needs to be properly sorted, the way its mounted is not good, too many interfacing layers that will allow movement.
My top slide is secured into the cross slide in a very similar fashion. The pins that clamp the top slide on mine are machined at an angle that matches the taper at the bottom but do not close into the waist of the groove. This means that when the pinch bolts are tightened the top slide is firmly pulled down onto the top of the cross slide mounting face.
When parting you should have the cutting/parting point as close to the chuck as is practicable. Whilst using a live centre to support the workpiece is OK, it can jam and break the blade, so if you have to provide support like that, then back the tailstock off just before you finish the cut.
I made a new tool holder for my Myford lathe and got rid of the expensive QCTP and the four way tool holder in favour of a "Norman" patent one. I also made a similar one for a rear tool post, which I currently use for a parting tool blade.
It would make a very good learning project for the lathe. I did a write up for it on here.
https://metalworkforums.com/f303/t20...orman+toolpostBest Regards:
Baron J.
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24th Jun 2021, 02:34 AM #85Member
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Thank you, Yes there are 2 pins there they are angle cut to fit with the compound slide insert.
and yeah, when i took it apart i thought i would need another one, perhaps my one is home made 'shrugs' but it's the hole in the middle being too large for the bolt that makes me think i need another.
Thank you. unsure which way i would go, 4 way post or a quick change due to the ability to change height of the tool with the qctp quite easily. But i've read 4 way is more rugged.
yep, the pins are there for me as well and act the same way as far as i can tell.
The parting tool, the point was closer to the surface that i wanted to be flat and not left with that tiny little nipple, that's all. The tail stock support i put in because i just rather have it and not need it than need it and not have it but i agree parting as close as feasible to the chuck is best
I'll be doing more work tomorrow
I don't have the coin to get a new post, but i know now that it's a likely cause of my frustrations.
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24th Jun 2021, 09:39 AM #86Most Valued Member
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24th Jun 2021, 11:10 AM #87Most Valued Member
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If you have a drill press or are able to drill holes accurately and some threading taps you can make your own 4 way post to suit what you want on the lathe, no milling required.
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24th Jun 2021, 06:17 PM #88
It would make a very good learning project for the lathe. I did a write up for it on here.
https://metalworkforums.com/f303/t20...orman+toolpostBest Regards:
Baron J.
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24th Jun 2021, 07:17 PM #89Senior Member
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Qctp
My lathe came with a rocker, but I soon swapped a QCTP in place. Never looked back.
So I bought a second QCTP, for the CNC lathe. Guess what: The tool holders are not strictly compatible between the two!
Not a problem: a 0.8 mm shim down one or both angled sides on one unit makes it all perfect. For a given value of perfect. But they do work very well for me.
Cheers
Roger
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24th Jun 2021, 10:57 PM #90
Hi Rodger, Guys,
I'm sure that you know my opinion about QCTP's ! They are great time savers in a production environment and I don't have a problem with that. But for hobbyists use they are an expensive toy !
I got seduced by people telling me that they were better than sliced bread. To hell with the initial cost of the toolpost and all the tool holders you have to buy to keep up with the Joneses. I don't need or want to spend a small fortune on insert tooling just so that I can save the ten seconds that it takes me to change a tool, or the extra seconds that it takes to reset the tool height after I have just reground a tool.
OK I'm a hobbyist and I take my time and think about what I'm doing, yes I make mistakes like anybody else ! At least my mistake doesn't cost production.Best Regards:
Baron J.
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