How can i fix lathe tool?

[Member 66061]

I stripped the threads in my tool tip. It was inevitable because the hole is only 2mm. The tool is 3/8".
I am stumped on how to fix this, so im looking for suggestions, maybe even ways to improve holding the tip, thanks.

 

[jimi_boom]

What about a thread insert like a helicoil? not sure if you can get one that small, and I don't know a lot about the tools either.

 

[PhillipM]

Bond/braze a locating dowel in the stripped hole, make a clamp that bolts down over the top to secure the insert, with a new hole/thread tapped into the bar to mount it.
Generally gives a more rigid solution anyway.

 

[Richard.]

Don't know how well it would take but you could try a drop of 312 tig filler and drill and re tap it.

 

[optima21]

drill it out and use a nut under the tool holder

 

[Member 66061]

Bond/braze a locating dowel in the stripped hole, make a clamp that bolts down over the top to secure the insert, with a new hole/thread tapped into the bar to mount it.
Generally gives a more rigid solution anyway.

Good idea, im going to have to think of how to do this.

 

[Seadog]

It looks to be one of the very cheap ones that I think RDG, and probably others, offered some years ago. I had a set that came with my lathe in 1991, complete rubbish. Slack threads, cross head screw and poor location of the insert. If you can afford it buy some better holders and inserts. I've been slowly building up a collection of tools and QCTP holders, well worth the expense in my opinion.

 

[brightspark]

cheap soft steel tool holder. decent ones are hardened and rarely strip the threads

 

[WorkshopChris]

Could you drill and counter boar out from the other side then turn up and press in a threaded insert.

 

[langy]

cheap soft steel tool holder. decent ones are hardened and rarely strip the threads

Yup exactly that

 

[hareng]

Might have to cut your losses easy way out.
If re thread another pitch, screw may not go through the insert.

If its the actual tool insert thread isn't stripped may be sub 0.3mm pitch and look stripped. There are numerous off the shelf screws M2.5, M3, M3.2, M3.5 each with a range of pitches and expensive J&L around £11 each.
Should be able to pick up a decent second hand non Chinese tool for about £20-30 that size, world of difference.

 

[Member 66061]

It looks to be one of the very cheap ones that I think RDG, and probably others, offered some years ago. I had a set that came with my lathe in 1991, complete rubbish. Slack threads, cross head screw and poor location of the insert. If you can afford it buy some better holders and inserts. I've been slowly building up a collection of tools and QCTP holders, well worth the expense in my opinion.

cheap soft steel tool holder. decent ones are hardened and rarely strip the threads

Yup exactly that

I knew i would get this, its not as helpful as the other replies though.
They came with allen head screws but i replaced them with longer stainless screws so i could tighten them down better. The reason it stripped is it is only 2mm and i tightened it harder than any 2mm thread could stand. It is only a small lathe, and i got it for nothing. These indexable tools are way better than the brazed tip ones i have. I cant afford to buy more tools, ive had some rotten luck lately and have lost more than i can afford, im skint.

 

[awemawson]

Drill it out to 2mm clearance and put a nut under the holder ?

 

[mfletch]

drill it out re-thread with bigger size Loctite it in then re-drill and tap to proper size

 

[brightspark]

may not be helpful but cheap tools are cheap for a reason get some good quality second hand hss tipped tools and sharpen them yourself thery last years and will cut virtually any material u will use unless your cutting cast iron en 19 and stainless a lot

 

[Seadog]

The reason it stripped is it is only 2mm and i tightened it harder than any 2mm thread could stand.

If you're using small tips the screw will typically be 2mm x 0.4. These are tough and have a Torx head. believe me you'd have to go some to strip one of those. Without wishing to labour the point, the reason you needed to tighten the insert so much is because of the poor design of the holder and insert. A decent holder and screw will not strip.

 

[Bill Edwards]

I can't see any reason not to drill right through and use a nut and bolt, it seems so easy.

 

[Hood]

The design of that tool relies on the screw holding the insert stationary and takes the majority of the cutting force. A decent tool will have two sides to the pocket and the screw will only be locating the insert rather than holding it.
Not sure what size of tool it is but if 12 or under then you can get a Glanze tool for £20 or so, they are fairly good tools and the pockets are designed properly.
If it is bigger than 12mm square shank then get a Korloy, they are decent tools and Cutwel often has them at around the £20 to £25 mark.

Edit, see you said it was 3/8" shank, you can get a 10mm shank Glanze for £16.56 plus post.
http://www.glanze.co.uk/acatalog/Single_Turning_Tools.html

 

[ukracer]

The design of that tool relies on the screw holding the insert stationary and takes the majority of the cutting force. A decent tool will have two sides to the pocket and the screw will only be locating the insert rather than holding it.
Not sure what size of tool it is but if 12 or under then you can get a Glanze tool for £20 or so, they are fairly good tools and the pockets are designed properly.
If it is bigger than 12mm square shank then get a Korloy, they are decent tools and Cutwel often has them at around the £20 to £25 mark.

Edit, see you said it was 3/8" shank, you can get a 10mm shank Glanze for £16.56 plus post.
http://www.glanze.co.uk/acatalog/Single_Turning_Tools.html

He did say he was skint though.

 

[Bill Edwards]

If you want ways to position the tip better without spending then it can be done if it's a case of function over form.
Depending on what you have to machine it you can either put a blob of weld then shape it (carbide burr for example, if you have one) or probably more likely just weld a little piece of metal to go up the side of the tip. There're always ways.