gtn2 insert for shars 3/4 parting block kit

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umahunter

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I was wondering what inserts others have successfully used with the 3/4 parting blade and block from shars .I'm about out of the shars inserts and had bought some korloy bits off ebay but they don't fit well and sit to deep in the holder. I wanted to buy a korloy blade but the smallest korloy blade I can find is 26 mm. so I'm back on the hunt for inserts I was thinking of trying iscar but I'm open to opinions from others to see what they've successfully used in the same blade the bad thing is I have no local suppliers so I have to order everything thanks for any help I routinely part 2 inch 6061 aluminum thanks for any suggestions :) 20171023_201246.jpg
 
I use the Shars .125 HSS "t" shaped blade for everything. Aluminum, steel, brass, stainless, plastic, whatever. Touch it up on occasion, but it has never given me a single problem.
Shars 250-207 holder with Shars M2 1/8x 11/16x 5 blade.
 
I have the Shars 1in deep blade which uses the same inserts. This is working for me. Why not just get more GTN2 inserts from Shars?
 
Am not a hobbyist so bear with me. I do not like wedge insert tooling very much unless it is straight parting and even then they lack positive insert holding. Above all they do not enjoy cutting sideways, you will one day need to produce a groove wider then the tool and not want to plunge it 5 times per part. A clamp down tool will do so with a bit of finesse, excellent grooving and parting tools are made by many manufacturers including Kenna Metal, Widia/Manchester, Kyocera and Kaiser to name a few, Kaiser's Thin Bit tools are awesome for this kind of work as they stock left and right handed dovetail O-ring tooling.

Have been doing a face grooving op as one feature on this part for the last several days, it has not been fun. 6 parts total, over 25 hours and 300 Lb's. of chips so far.

 
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I've never been much of a fan of GTN inserts. I use Manchester Separator inserts. My Manchester tools don't have as of a deep capacity like a parting blade but that doesn't matter to me. Anything deeper I use the bandsaw for "parting". I much rather use the bandsaw when I can over parting.
 
I have a Shars parting tool but it uses GTN-4 inserts. I've had pretty good luck with them cutting aluminum, steel and 304 stainless. Normally drop down to back gear at ~150 RPM. As mentioned above, if you're happy with the Shars GTN-2's get some from them or shop on eBay. I just did a quick search on eBay and found many sources selling them for about $1 each.

I usually use a tapered-sided HSS blade and just touch it to the grinder before every use. I've also used the MGMN-200 and MGMN-300 with mixed results, usually OK.

Bruce
 
I favor a "T" shaped parting blade held in an angled tool holder for parting. Having seen your lathe I am not sure if you have room for one, but maybe if you turned your compound and adjusted the position of the tool post.

The problem with parting blades is they really only seem to be held well near the front of the blade holder. Atleast with the three I have (for different size parting blades) This means the back sometimes swings out. I am sure a more experienced machinist (or some might say a real machinist instead of a lowly button pusher) might have an answer for that. I think it partly has to do with the geometry of the leading edge. When you sharpen it you cut it slightly angled on purpose to leave the burr on the stock instead of the part. I think this leads to the blade being pulled out of position if you part aggressively. Joe Pieczysnki doesn't seem to have a problem with it on his YouTube videos so I am sure I am missing something there. I seem to recall he usually leaves the burr on the piece that falls off. This would hold the blade against the tool holder. Since you are parting off the work piece if I understand the may you make your part that would leave the burr on your finished part.

That doesn't mean you need to re-chuck the part to clean it off. I often wind up with a burr on a work piece. Often I can just tear it off with a pair of pliers, and then clean the hole with a simple swivel blade deburring tool. I'm sure you know what that is, but if you want to stop by my shop I have four of them. I'd be glad to loan you one for a week or so. They are cheap, and even the local box plumbing stores have them pretty cheap in the plumbing department. I am pretty sure I saw one in Home Depot the other day next to the inside pipe wrenches and pipe nipple ez-outs.
 
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