[How do I?] Select QCTP Carbide Holders?

ACHiPo

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I pulled the trigger and ordered a used Aloris QCTP for my Logan 816 lathe. It comes with 6 tool holders. I'll use the 3/8" HSS tools in several of the holders, but I'd like to get a few indexable carbide holders, and am not sure where to start. I did watch the "New Old Tony" video which helped, but I'm still confused.

I'd like to get a multi-purpose carbide insert holder that I can use for most of my lathe operations. I think Tony suggested a WMNG, but I'm not sure that would be a good choice for the anemic motor on the Logan?

I'd also like to get a tool holder I can use for threading.

Thanks in advance for your advice.
 
WNMG is not an insert for a small lathe IMO. I think a positive rake insert would serve you much better. WNMG likes to take a cut, relatively quick feed rate and speed. Fast feed, heavy cut and speed are not usually associated with things that small under powered lathes do well. Throw in lack of rigidity and you have a recipe for unhappy outcome. Maybe try hand ground HSS tools for a while then go with positive rake inserts or quality (Micro 100) brazed carbide.
 
I'd like to get a multi-purpose carbide insert holder that I can use for most of my lathe operations. I think Tony suggested a WMNG, but I'm not sure that would be a good choice for the anemic motor on the Logan?

I'd also like to get a tool holder I can use for threading.

Thanks in advance for your advice.

I'm by no means an authority on the matter, but I have found CCMT inserts to work really well on my lathe (320 mm x 920 mm with a 1.5 kW motor). That should be a 13" swing, if I have got the conversion right.

I have both a right-hand turning tool, and a boring bar that takes the same size insert, which helps. CCGT inserts also fit, and work great on aluminium.

Only downside is that you only get two cutting corners on normal holders, but you can get facing holders to use the remaining corners.
 
I'm by no means an authority on the matter, but I have found CCMT inserts to work really well on my lathe (320 mm x 920 mm with a 1.5 kW motor). That should be a 13" swing, if I have got the conversion right.

I have both a right-hand turning tool, and a boring bar that takes the same size insert, which helps. CCGT inserts also fit, and work great on aluminium.

Only downside is that you only get two cutting corners on normal holders, but you can get facing holders to use the remaining corners.
A CCGT is a diamond-shaped ground tool with a relief angle, correct? That would seem to have a very sharp edge and require less power, which would be great. The downside seems to be the edge fragility and there are only 2 cutting surfaces, so each one costs ~$8.

Can I use a CCMT/CCGT tool for threading, or will I need a special tool for that?
 
A CCGT is a diamond-shaped ground tool with a relief angle, correct? That would seem to have a very sharp edge and require less power, which would be great. The downside seems to be the edge fragility and there are only 2 cutting surfaces, so each one costs ~$8.

Can I use a CCMT/CCGT tool for threading, or will I need a special tool for that?

I only use the CCGTs on aluminium, so they actually last long in my experience.
The CCMTs are also pretty efficient. When I cut 4140, the fear of flying hot chips is the limiting factor, not the power required by the cut.

You will require completely different inserts and holders for threading - I still thread with HSS.
 
ACHiPo, you are discussing an SCLCR (rh) or SCLCL (lh) tool. This is the tool holder designation. This tool has a 5 degree positive lead so that it can both face and turn without moving the tool holder. It holds either CCMT or CCGT inserts. The former is used for most materials, while the CCGT inserts are usually used for aluminum. Both are positive rake inserts with two cutting tips. There are some tool holder sets that include a tool that will use the other two points but their utility is limited; AR Warner is one such company that offers these sets.

Typically, a 3/8" tool holder will take CCMT22.51 inserts for general work and a CCMT22.51 AK insert for aluminum. The CCGT has a very positive rake at the tip and is very sharp; at high speeds, this insert will rival HSS. Both are capable of heavy cuts taken at high speeds and feeds. If you must run inserts, this is probably the single most popular geometry in hobby shops. Cutting forces are lower than most triangular type inserts.

With that said, you have to remember that your Logan is a fairly small, light lathe with limited rigidity, speed and power. It was made to use HSS tools, not inserts. Just because you can use inserted tip tools, that doesn't mean those tools will work as they should; they will not. They will cut, no doubt, but not as well as they would on a rigid, high speed lathe that is capable of taking the depths of cut the insert normally requires.

As Doubleeboy said, you are far better off using HSS tooling that your lathe was intended to work with. HSS will cut well at the speeds and feeds you have available and the tool geometry can be tailored to reduce cutting forces to maximize the efficiency of the lathe. Yes, these tools are old school nowadays but then again, your lathe is old school, too. The only issue with HSS is that you have to grind them. This is not difficult but there is a learning curve.

Another option that many hobby guys take is to use inserts made from HSS. These inserts have no chipbreaker and are readily re-sharpened. Again, AR Warner is the company to look to for these types of inserts and tool holders. While they work better than carbide, remember that their geometry is the same as a carbide insert so cutting forces will be higher with them as well.

I own SCLCR/L turning tools and AR Warner tools as well so my opinion isn't a guess. These tools work, but HSS will work better in almost every case. HSS will cut with lower cutting forces and will finish better than any of these inserted tools. Moreover, the sharper cutting edge and geometry of a properly ground HSS tool will deflect less than an inserted tool so they are potentially more accurate. You don't appreciate this until you try to shave off 0.0005" with that tool; HSS will do it but carbide ... not so much.

Another option is a high quality brazed carbide tool. These tools can be sharpened to a very sharp edge and you can grind a nose radius on them to improve finishes. However, their geometry (flat top) is such that they do cut with higher cutting forces vs HSS.

For a light lathe with low rigidity, speed and power, my opinion for turning tools would be HSS, brazed carbide and then inserted carbide. For thread cutting, I would use HSS, although some sharp inserted carbide cutters will work nearly as well. For boring, I would opt for inserted carbide used on a solid carbide shank (this choice is complicated and beyond the scope of this discussion).
 
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Mike,
Great advice. Thanks!
Evan
 
Just got this reply from Maineacs, a site specializing in carbide tools (and CNC computers?) for hobbiests. This Old Tony referenced them in one of his videos, so I dropped them a line. Unfortunately there wasn't much explanation on why they recommend what they do.

We would recommend the MWLN toolholder in either the 5/8 or 1/2 inch with the WMNG331 FF2 TP2501 insert. Have a great day and good luck with your machining.​
 
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Mikey, that's a great explanation. For a little further clarification and understanding, CCMT and CCGT (ignoring for now the digits that follow) are the same except molded vs ground, aren't they?

For the sake of trying out inserted carbide, especially for small boring operations where my homebrew attempts have been too flexible to be considered useful or effective, I ordered some a few weeks ago from eBay. But the designation is slightly different, specifically CCMT060204-HM YBC251. I don't know how much of that is specific to the generic Chinese model number, but I can't help but notice that the "251" at the end is at least reminiscent of the "32.51" and "22.51" you cited. Do you have any insight here?

I hate using eBay links in fora since the links will expire while the post will be around for a LONG time, but the item number for the sake of today's discussion is 322381018603.

Thanks!
 
I found it! In another listing CCMT060204 is cross referenced with CCMT21.51. :)
 
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