Author Topic: Carbide tool holder  (Read 2667 times)

Offline NormanV

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Carbide tool holder
« on: September 07, 2016, 03:19:59 PM »
This is a story of a mod., with a bit of knowledge and a lot to learn. Unfortunately I didn't take any photos of my progress as my camera was broken, but now that I have a new one there will be a shot of the finished item.
I bought a tool holder at an Autojumble (my first, I'll definitely go again). It had a 25mm square shank, my lathe tool holder only takes 16mm. No problem, just pop it in my homemade milling vice on my homemade milling machine. Using a 12mm HSS end mill I tried my first cut ( Huh, I need to get on and finish my Quorn!) I placed an order for a Carbide end mill, this was positive, I live in a holiday area and the seller has a caravan just down the road, so the cutter was delivered next day. I popped it in the mill and off I went. What a difference! Needle sharp splinters of steel were sprayed in all directions. I pushed it further, red hot splinters flew everywhere. Then it stopped, no warning no smoke, no nothing. It just stopped. I was quite worried, the wiring of this machine had stretched me to the limit. Trouble shooting was possibly going to be a step too far. 
Next morning I switched it on and joy oh joy, it worked. It must have been an overload in the speed controller. Although it was now working I was finding that the rate of metal removal was quite slow and I was worried that I would ruin the carbide end mill. Then I had a revelation, I ordered some 1mm thick cutting discs for my angle grinder. They arrived after 2 days, 30 minutes work had the tool holder roughed out and another 30 minutes in the mill had it machined nice and square. Phew, what a palaver! At least next time I will be able to do it more quickly.
I tried it out on a piece of mild steel, rotten finish, it is too late now I'll sort it out in the morning.

Offline Lew_Merrick_PE

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Re: Carbide tool holder
« Reply #1 on: September 07, 2016, 06:59:45 PM »
In my experience, a tool holder responsible for poor finish suffers from one (or more) defects.  (1) The foundation for the insert is not flat (usually from being hemstitched with a ball mill).  (2) The periphery locator os a poor fit.  or (3) the clamping arrangement does not hold properly.  I have reached the point where I made the foundation from a piece of CRS bar stock and silver solder the periphery locator in place (usually "sacrificing" an insert to assure alignment).  I have no photos, but I have been making insert toolholders this way since the late-1960's.

Offline Pete.

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Re: Carbide tool holder
« Reply #2 on: September 07, 2016, 07:24:23 PM »
Wind your rpm up and take healthy cuts, see if the finish improves.

Offline chipenter

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Re: Carbide tool holder
« Reply #3 on: September 08, 2016, 01:59:33 AM »
Is that a cutting incert or the anvill ? I have never seen a TN incert with a flat top like that before .
Jeff

Offline awemawson

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Re: Carbide tool holder
« Reply #4 on: September 08, 2016, 02:58:18 AM »
Norman, as chipenter says, it certainly looks as though you have no insert in the holder, and are cutting with the carbide seat that the insert should locate on.
Andrew Mawson
East Sussex

Offline John Rudd

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Re: Carbide tool holder
« Reply #5 on: September 08, 2016, 03:52:38 AM »
I think it looks like a very cheap,TCMT insert.....the sort bought at car boots for about 50p.....

As said, try winding up the speed, it is cutting on centre height yes?
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Offline NormanV

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Re: Carbide tool holder
« Reply #6 on: September 08, 2016, 05:37:58 AM »
That was the insert that it came with. I have got some others with chip breaking grooves in them I'll try them tomorrow, I've got a load of cooking to do today.
I tried it on the fastest speed and yes, it is a centre height.

Offline Manxmodder

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Re: Carbide tool holder
« Reply #7 on: September 08, 2016, 06:15:04 AM »
Is that a cutting incert or the anvill ? I have never seen a TN incert with a flat top like that before .

It does indeed look very much like there is no actual cutting insert and just the shim/anvil present in the photo....OZ.
Helixes aren't always downward spirals,sometimes they're screwed up

Offline awemawson

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Re: Carbide tool holder
« Reply #8 on: September 08, 2016, 06:22:56 AM »
Norman, does the screw that locates what your are using as an insert have a centrally drilled and tapped co-axial hole? If so your are cutting with a carbide seat, and the cutting insert is not fitted ! It would be located by a second screw into that hole.

Usually the insert top surface is pretty well level with the top of the holder which is another clue that the insert is not fitted.
Andrew Mawson
East Sussex

Offline NormanV

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Re: Carbide tool holder
« Reply #9 on: September 08, 2016, 08:27:31 AM »
 :doh:
I've never seen a carbide tool holder up close before. It certainly is as mentioned by others.
I've been wasting my time with this holder, with it in its lowest position the support piece is exactly on centre height. I need to take another 3-4mm off the height of the holder.
Where can I buy the fixing screw to hold the cutter? I don't have any screws that fit.
I'm glad I posted my story, I would have carried on groping in the dark without your help. Thank you all.

Offline Jo

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Re: Carbide tool holder
« Reply #10 on: September 08, 2016, 09:00:18 AM »
Norm,

Are there any letters/numbers written down the side of the holder?

The holders are normally hardened, the better quality the holder the harder they are.... as a minimum you will need a carbide milling cutter to do it.

I have had some success buying Chinese tool holders. They are not as hard as quality ones but are ok.

Jo

P.S. I have found one cheap Chinese supplier that is selling boxes of 10 Japanese Mitsubishi CCMT09T304 tips on Fleabay for less than 8. So far I am pacing myself and have only brought 4 boxes  :coffee:
So many engines to build and yet so little time.

Offline Manxmodder

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Re: Carbide tool holder
« Reply #11 on: September 08, 2016, 09:04:31 AM »
I often buy screws for insert holding from here: https://www.shop-apt.co.uk/torx-screws.html

What brand of tool is it?......OZ.
Helixes aren't always downward spirals,sometimes they're screwed up

Offline seadog

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Re: Carbide tool holder
« Reply #12 on: September 08, 2016, 09:07:26 AM »
i use shop apt all the time. Expensive but good kit and a fast turn-around.

Offline Manxmodder

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Re: Carbide tool holder
« Reply #13 on: September 08, 2016, 09:09:51 AM »
TCMT inserts of various sizes and material cutting types:https://www.shop-apt.co.uk/carbide-inserts-for-turning-apt/page/5/
Helixes aren't always downward spirals,sometimes they're screwed up

Offline Manxmodder

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Re: Carbide tool holder
« Reply #14 on: September 08, 2016, 09:13:58 AM »
Lathe tools of a similar pattern to yours that use  TCMT inserts.

https://www.shop-apt.co.uk/apt-93-stjcrl-lathe-turning-tools-for-tcmt-inserts.html
Helixes aren't always downward spirals,sometimes they're screwed up

Offline chipenter

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Re: Carbide tool holder
« Reply #15 on: September 08, 2016, 01:48:38 PM »
The numbers if any on the side of the tool will give the type and size inserts used , it looks to have a forward slope so a negative insert in neaded ,
Jeff

Offline tom osselton

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Re: Carbide tool holder
« Reply #16 on: September 08, 2016, 02:16:33 PM »
I ordered 6 screws from Busy Bee to replace one that rounded the hex it took a good two months to get them!

Offline mechman48

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Re: Carbide tool holder
« Reply #17 on: September 29, 2016, 06:08:58 AM »
Is that a cutting incert or the anvill ? I have never seen a TN incert with a flat top like that before .

It does indeed look very much like there is no actual cutting insert and just the shim/anvil present in the photo....OZ.

As I see it you are definitely cutting with the carbide anvil; there should be an insert in there that would bring it level with the top of the holder.

George.
George.


Always look on the bright side of life, & remember.. KISS..' Keep It Simple Stupid'