Thread: Too much rigidity?

Ok, I think I see how that works now. That's quite clever.

[We need our own 'Homemade Tools / Neat Ideas' thread guys.]

Originally Posted by Bryan

Ok, I think I see how that works now. That's quite clever.

[We need our own 'Homemade Tools / Neat Ideas' thread guys.]

As you have moved that motion, I'll second it

Well here's my attempt at a quick & dirty parting tool, using a power hacksaw blade. It's inspired by Stuart's design, but I dumbed it down. Didn't even bother milling a slot, just made the screws a snug fit. I just wanted to test the hacksaw blade idea. The results are not encouraging so far. Worked fine in aluminium, but only got about a mill into the steel bar shown. I thought it was mild steel, it seemed to file ok. Will have to try turning it to see if it cuts normally.

Would the material be uniform in those blades, or harder at the cutting edge? Maybe I'll try the other side. There's something else I might try, an old cold saw blade, presumably HSS. It's about 3mm thick, where the hacksaw blade is only 1.6. I have a feeling heat is a big issue with such a small blade. I mean parting blades in general. I don't have coolant, just cutting oil. Parting is one time I would like coolant.

Sorry I think the pics have reordered themselves.

Hi Bryan "shatterproof" worries a little, I'd guess that means flexible i.e. not hard. I think most good hacksaw blades are only hardened on the teeth. So you may do better with the blade the other way up, dont grind to deep removing the teeth so you are using the hard side of the blade.

I think the cheaper blades are hardened all the way through, thats why the cheap ones snap like carrots.

As far as your holder goes, it works for me, as long as the blade is vertical(although if we can't get it cutting deeper than 1mm thats not going to matter )

Stuart

Originally Posted by eskimo

As you have moved that motion, I'll second it

Thirded! I have one or two, not very interesting. Always great to see what people come up with in these sort of threads!

Hi Bryan,
A couple of years ago I discovered a parting off setup that works for me. It's a Mitsubishi holder with TC inserts They are only about 2.00 mm wide so that cuts down (pardon the pun) the kerf so therefore greatly reduces the power needed. they are double ended so 2 for the price of 1. A couple of days ago I replaced the first insert after about 3 years, but the lathe wasn't used for 14 months. I probably don't do a lot of parting but a box of 10 inserts is going to last for quite awhile. Last week I cut through a 100 mm diameter bar of mild steel with no problems. One of the secrets is that the profile of the tip causes the swarf to bend in a shallow v before it curls up (like a steel tape measure) this reduces it's width & therefore doesn't jam. There is a pic on page 2 under the "Parkerizing" Thread
Ian.

Ian, that sounds pretty good. Did you buy that locally, and do you remember the cost at all? I couldn't find a holder like yours on the Mitsubishi website: MITSUBISHI MATERIALS CORPORATION##Turning. I'm guessing it wasn't cheap, but probably worthwhile in the long run. Being on a tight budget makes the short term more pressing though. And as soon as I start reading about carbide inserts I feel like I'm opening a Pandora's box of ever-increasing cost and complexity.

I had another look at my hacksaw blade today. Anyone with eyes and a brain would have seen that it was a 2 part blade, and I'd cut off the best bit. So I made another blade and it was better, but not good enough. It didn't wear the edge and completely stop cutting like before but it still wanted to overheat and dig in. So I'm losing interest in that idea. Maybe I'll keep it for al. [Yes it was just below centre. 7 deg front clearance, tried 0 and 3 deg rake.]

The seller of the broken holder has agreed to a discount on a replacement so I think I'll take that option as a stop-gap, and get a gravity coolant bottle set up just for parting. Later when I've got a few less projects nagging at me I'll look into a rear mount toolpost.

What Dia is the bar? What rpm are you using? It shouldnt be getting that hot unless it is rubbing somewhere.

Stuart

The bar is 28mm. Speed is 280 rpm - my slowest.

How deep are you getting? you're sure the blade is vertical and at 90degs to the spindle? Is it MS? Are the gibs on your crossslide tight?
You might be right it might be time for it to go in the spare parts bin.
I've never tried it with a HSS blade or a blade that size.
Stuart

Originally Posted by tinkera

. There is a pic on page 2 under the "Parkerizing" Thread
Ian.

it is?...is it the first one top left?

is this the type of parting tool your talking about

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Stuart, the cross slide is probably the weakest link in my whole setup now. There's a ton of backlash in the leadscrew, and you can't adjust the gib properly cos it changes along it's travel. On one setting it will bind before it reaches full out, and be sloppy before it hits centre. I've got a t-screw fitted to the gib so I can ride it a bit but it's a fine line. I think I understand the issues - enough to know there's not going to be a quick fix. In time I'll start a thread about my cross slide. Have a couple of other fish to fry right now.

My cross slide could use some work, but that will have to wait until I have a big enough surface plate
Godd luck
Stuart

Hi Bryan,
Sorry I didn't get back to you earlier, just a bit hectic, I bought the parting tool holder & inserts locally ( in Adelaide ) before I moved. The company was called Metal Cutting Technology, I think) They were the agents for Mitsubishi, the sales agent would call at my home with what ever tooling I phoned about. I don't think they exist in S.A. at the moment as there is no listing in electronic white pages. They do have a Melbourne No. & I can phone them for you if you want me to. I can phone them for no charge. I don't remember the cost but at a guess the box of 10 inserts would have been about $70.00 double ended so only $3.50 per tip.The first insert has lasted about 2 years of use so the box should last forever. I am guessing I paid about $130.00 for the holder & a special spanner that opens the holder to replace the tip. I had to make the holder to fit the blade to my tool post. hope this helps.
Ian.