# Q-Cut parting tool



## vcutajar (Dec 22, 2011)

This week I received the Model Engineers' Workshop issue 185 and there was an article which caught my eye. It was about using tipped lathe tools and in it there was mentioned the Q-Cut parting system.

http://www.greenwood-tools.co.uk/shopscr23.html

http://cheappartinginserts.bombog.c...sert-gc1125-grade-r151-shape-high-feed-0-012/

I was looking at the profile of the insert and it seems very similar to the grooved or bifurcated profile that Edgar T. Westbury describes as a tool for making crankshafts.

Has anybody here used this tool with any success especially in making crankshafts?


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## crankshafter (Dec 22, 2011)

vcutajar.
I use simular bits for cutoff. I dont recomend using them for turning crankshafts in models whith so small dia. shafts(flexing). Grind you up a HSS cutoff-blade, trying to get the profile like the bits you looking at 
Just my 2 c.
CS


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## kuhncw (Dec 22, 2011)

As usual, you will get differing opinions as there are many ways to do a job and that is partly what makes this hobby so interesting.

I used an Iscar cutoff blade and insert to machine the journals on my Silver Bullet crank. I cut much of the material out on the mill to speed things up. I then used right and left hand brazed carbide to finish up the cheeks of the crank throw. HSS would work just as well for the journal and crank cheeks. The stroke for this engine is 0.75 inches. This sort of tool does not work as well as stroke increases because the blade must be extended further. Anyway, this setup worked well for me on this crank.

Regards,

Chuck


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## vcutajar (Dec 22, 2011)

Thanks crankshafter and kuhncw for your feedback. Another thing that would worry me would be that the tips would not last long with interrupted cuts.


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## kuhncw (Dec 22, 2011)

I had no problem with damage to the cutoff insert from the interrupted cut. The crank material is 1144 steel. I ran fairly slow, brushed on some cutting oil now and then, and didn't take heavy cuts. The insert is still in the holder several months later and cuts off stock with no problem.

These inserted cutoff blades are a bit expensive, but they really take the pain out of cutoff work.

Regards,

Chuck


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## deverett (Dec 22, 2011)

I bought a Q-cut setup from Greenwood Tools some years ago following a rave review. However, I must be doing something wrong because I can't get decent results from it - either in the front or rear toolpost on my Myford.

Materials were mainly various grades and diameters of steel.

I have tried setting it dead on centre height and a bit below. I have tried slow speeds (bottom direct) up to 640rpm (max speed in direct drive). I have tried slow feed, fast feed. With cutting fluid and without. 

I have returned to using HSS Eclipse blades with reasonable success and for small diameter stuff, I use broken off hacksaw blades with great success.

Replacement tips from Greenwood are not exactly cheap whereas broken hacksaw blades are plentiful!

Dave
The Emerald Isle


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## Blogwitch (Dec 22, 2011)

The Q-cut you show is in fact the Mk2. I have the Mk1 version, and because it is of a completely different design, the insert is clamped by a screw, it is much more rigid.

This new design has been copied all over the place by everyone and his dog, and IMHO is nowhere near as good as the original design.


John


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## purpleknif (Dec 22, 2011)

The tool you show is the only Iscar product I've ever been disappointed in. I've been a machinist for 30 years and I think that tool is junk. So does everyone else where I work.


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## Springbok (Dec 22, 2011)

Yes Dave
I tend to use an old eclipse hacksaw blade case hardened for small slots like this and if it happens to go fut no great a loss
just make another but I must say I case harden a number at the same time. 

Bob


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## deverett (Dec 22, 2011)

Bob

I use the 'all hard' type hacksaw blades, and they do not need any form of heat treatment.

Dave
The Emerald Isle


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## kuhncw (Dec 22, 2011)

[
 "The tool you show is the only Iscar product I've ever been disappointed in. I've been a machinist for 30 years and I think that tool is junk. So does everyone else where I work."
[/quote]

Hi Purpleknif,

Sounds like you don't care much for the Iscar cutoff tooling. What is it about this Iscar tool that gives it such a low reputation with you and your fellow machinists? I've had good luck with it in a home shop setting, but maybe I'm missing something. What cut off tool do you recommend?

Regards,

Chuck


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## Blogwitch (Dec 22, 2011)

Chuck,

I too don't reckon much to the new version either. The old clamp version was much better and a stronger design. The way the new one just has the 'slide' in tips is the weak point, after a time, the holder metal just can't take the cutting forces and loses grip of the tip.

I actually now use a large Mircona for doing most of my parting off. As you can see, it has a clamp to hold the tip in and plenty of rigid support underneath. This one can be used for most all turning jobs as well because it can be fitted with a complete range of different tips, if it can get into the job, it will cut it, facing, parting, right and left hand cutting, it takes on almost anything.

[ame]http://www.youtube.com/watch?v=BG4qEw3eMcQ[/ame]

If you really want to see what they can do, have a look at this video, and even though under CNC, whatever it can do, you can do the same thing manually. I use both the flat face and the round nosed inserts, whichever I can pick up cheaply off ebay.

[ame]http://www.youtube.com/watch?v=8bDIEwj6UW4&feature=related[/ame]



John


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## MachineTom (Dec 22, 2011)

You should note that the speeds are beyond what most lathes owned by forum members are capable of. The steels were running at 540 ft per minute, thats a 1" diameter piece turning at 2150rpm, a .5" D at 4300. Chips really fly at that speed. THe coolant was turned off for those shots,(I assume) as tool life would suffer for chip welding at those high speed after a short time.

Carbide really comes into its own at speed, but you need the lathe able to handle the forces of cutting as well as the spindle speed. A .100 tip with no positive rake on a mini lathe is not a good fit. As was found out by a poster in the" Goofs" Forum.

Brazed carbide tip cutoof tools are cheap and last years, if it chips just dress it back with a diamond wheel.


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## kuhncw (Dec 22, 2011)

Hello John,

The Mircona looks like a nice design. I've seen this design and I see that Travers carries a similar tool with the Walter Valenite name.

http://www.traverscatalogs.com/lg_display.cfm/catalog/Master_2011/page/401

I'll take a good look at this type tool. I have, as you mentioned, sprung the insert holding feature on the Iscar, once when chips built up and I jammed the tool. 

Thanks.

Chuck


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## Blogwitch (Dec 23, 2011)

Chuck,

That is roughly the design of the original Q-cut, a much better design as far as I am concerned, unfortunately rather expensive, that is why I went ebay hunting to get all my specialist tools. I managed to get them all for around 10 to 20% of the normal costs, and they were all brand new. It was just a waiting game for the right ones to turn up.

Tom,

One of the major failures in parting off for beginners is that they follow the advice of the unknowing, and try to part off at too low a speed, and are also scared of the technique, expecting problems to occur. 
Parting is just another technique to be learned, just like all the other machining techniques, once you get the hang of it and don't let it scare you, it is just like turning to size.

The max speed I use on my lathe is 980 on the lower range (which is what I use all the time) and I find that will cope with all the parting I need to do. In fact, I will part off a big piece rather than using my power hacksaw, it is much quicker.


John


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## Swede (Dec 23, 2011)

I've got that exact Iscar blade, and the Dorian AXA block, and I absolutely love the combination. For profiling work, it's easy enough to turn a L or R carbide insert into one with a flat face using a diamond wheel. Obviously it likes being plunged best, but you can take left and right cuts if kept small.

The Dorian block or clones of that style is a great tool IMO. Really holds the blade properly, and it also allows extension or retraction quickly and easily.


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## Niels Abildgaard (Dec 24, 2011)

If You search here for    selecting and using bob g   and take ten minutes to read the whole thread ,parting fear (and free-cash) can be a thing of the past . 

I do not know how to link but I can offer a picture of the best and most expensive amateur cut off system


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## purpleknif (Dec 24, 2011)

kuhncw  said:
			
		

> [
> "The tool you show is the only Iscar product I've ever been disappointed in. I've been a machinist for 30 years and I think that tool is junk. So does everyone else where I work."
> 
> 
> ...


 At home I make my own out of high speed. At work we find the Valenites are much better. That said, I gotta say anything Iscar makes is about the best stuff there is.


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## smfr (Dec 24, 2011)

Niels Abildgaard  said:
			
		

> If You search here for   selecting and using bob g


I think you're referring to this thread: http://www.homemodelenginemachinist.com/index.php?topic=10922.0

Looks like a good read, thanks!


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## Niels Abildgaard (Dec 24, 2011)

Hello SMFR and merry X-mas

Thank You for linking to the thread I meant

Regards

Niels


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