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View Full Version : Brazed Carbide Toolbits Wearing Prematueley?



Andre3127
10-27-2016, 08:08 PM
I have a small job to do, making 35 or so buttons for shooting coats. They are made from 1" diameter cold rolled steel, and for a 1/4" length are turned down to a .300" diameter. I have turned about ten of them with the same brazed carbide lathe tool, pulling a nice blue chip taking a fairly deep pass with a .0015 feedrate at about 700-800 RPM. I reduce this diameter over a few passed. I noticed finishes starting to deteriorate and feed forces getting much higher, just to find a flat spot right along the cutting edge. I expect carbide to wear like this, but it seems a bit premature and I'd think it would last longer. I do not know what grade of carbide or brand of toolbit, they came with my lathe and I touched it up with a diamond file before use.

I plan to change to HSS for roughing, since I don't have a diamond wheel to sharpen these carbide tool bits, and insert tooling is not economical for my uses. I am not using any cutting oil in fear of shocking the cemented carbide, and do not have coolant.

Do I just have crap toolbits? Are my expectations too high?

mattthemuppet
10-27-2016, 08:23 PM
maybe you have the grade for aluminium/ CI (C5?) instead of steel? I think the alu/CI grades are supposed to be more abrasion resistant and the steel grades are tougher.

given the price of indexable carbide tooling out of China, I can't see why you would want to stick with brazed carbide unless you just wanted to use them up. 10 and 12mm holders are $6-8, inserts are $10-15 for ten or less. I got 10 CCMT 21.51 for $5 the other day and they cut just fine - great for roughing and interrupted cuts. Then I use CCGT inserts for finishing. I've knocked the tip off one CCGT insert in the 6mths or so I've been using them and all of my indexable tools use the same size CCxT inserts, so I only need 1 box of each.

I used to be big on HSS, but even these cheap tools are so much better, let alone more convenient. I can run the piece faster, get better finishes and don't have any material buildup on the work, which was a real pain with alu and HSS.

Andre3127
10-27-2016, 08:43 PM
maybe you have the grade for aluminium/ CI (C5?) instead of steel? I think the alu/CI grades are supposed to be more abrasion resistant and the steel grades are tougher.

given the price of indexable carbide tooling out of China, I can't see why you would want to stick with brazed carbide unless you just wanted to use them up. 10 and 12mm holders are $6-8, inserts are $10-15 for ten or less. I got 10 CCMT 21.51 for $5 the other day and they cut just fine - great for roughing and interrupted cuts. Then I use CCGT inserts for finishing. I've knocked the tip off one CCGT insert in the 6mths or so I've been using them and all of my indexable tools use the same size CCxT inserts, so I only need 1 box of each.

I used to be big on HSS, but even these cheap tools are so much better, let alone more convenient. I can run the piece faster, get better finishes and don't have any material buildup on the work, which was a real pain with alu and HSS.

May I ask where you buy your inserts? That's not a bad price at all, in fact I'm willing to make my own adjustable angle holders anyway.

J Tiers
10-27-2016, 09:02 PM
Get some diamond honig sticks from a woodworker place, or maybe HF. They work fine, and the coarse cuts fast.

You should be ok as it is around 200 SFM, ok for carbide. Wrong grade most likely, as carbide lasts well for me with 4140PH material, that just eats HSS.

BCRider
10-27-2016, 09:37 PM
Andre, I've run into the same thing with the brazed tools. But I freely admit that I never looked into which grades each is and what they are good for. I try them and if they chip or burn the edge off I switch to another until I find one that works. It's crude I know.

When I find the right one they do work well. And the fact that the chips were coming off blue suggests that the edge was eroding earlier than you suspect.

For this stuff Ebay seems to be our friend. A quick check for CCMT inserts turned up a lot of options at anywhere from $13 for 10 to $30 for 10. If you don't have an Ebay account it may be time.

JoeLee
10-27-2016, 10:30 PM
CR is rough on any tooling, even carbide. The only time I get a good finish on CR is when I use a TPG insert KC 730 grade, dead sharp, not a honed edge insert. I think your cut may be a little too deep and the speed a little to slow.
A better choice of material would have been 1215.

JL..............

Andre3127
10-27-2016, 10:36 PM
Can't do anything about speed, the next higher pulley slips on the old flat belt. That belt is on my list of things to fix/replace.

These carbide tools are great, I've turned dead hard HSS and cast iron brake rotors, HSS didn't even scratch those rotors.

I have diamond file on my leatherman, it works great and touches up these toolbits, but honing out a flat spot on the edge takes time, I'd rather quickly sharpen a HSS tool in a quicker amount of time. I didn't go with HSS originally because I figured the carbide would last a lot longer. Lesson learned :)

J Tiers
10-27-2016, 11:27 PM
A diamond file may not be the same thing. Don't judge the honing sticks by your Leatherman "diamond file"

The honing sticks can really take off material pretty fast, I had no problem reshaping carbide back when they were my only method. Especially the coarse grade. I bet you'd find the real thing was WAY better than the "all-purpose diamond file" on the Leatherman.

mattthemuppet
10-28-2016, 12:30 AM
May I ask where you buy your inserts? That's not a bad price at all, in fact I'm willing to make my own adjustable angle holders anyway.

for sure - I got my CCMT from Banggood
http://www.banggood.com/10pcs-CCMT060204-HM-YBC251-Carbide-Insert-Titanium-Coated-Carbide-Cutter-p-1055821.html?rmmds=search

the CCGT from eBay
http://www.ebay.com/itm/10pcs-CCGT060204-AK-CCGT21-51-AK-Used-for-Aluminum-superior-quality-/291920353212?hash=item43f7cf17bc:g:aBcAAOSwc1FXZjE O

my boring bars and internal threading bar from Banggood (already had a Shars 3/8 bar)
http://www.banggood.com/SCLCR-6x100mm-and-12x150mm-Lathe-Boring-Bar-Tunring-Tool-Holder-With-2Pcs-CCMT0602-Insert-p-1053304.html?rmmds=search
http://www.banggood.com/SNR0010K11-10125mm-Lathe-Turning-Tool-Boring-Bar-Holder-For-11NR-A6011IR-A60-Inserts-p-1063214.html?rmmds=search

plus a couple of 10mm RH turning tools
http://www.banggood.com/SCLCR1010F06-10x100mm-Lathe-Turning-Tool-Holder-With-a-CCMT060204-Insert-p-1063217.html?rmmds=search

so not a whole lot of outlay and I'm set for a good while. Next pay check I'll get a couple of 10mm SCMCN holders for doing face and side bevels and then I should be more or less done. A 12mm internal threading bar with an AG60 insert would be nice, but I don't do enough threading to justify that.

oh, and those CCGT inserts can take a 1/2 thou cut easily (1 thou diameter) and they leave a beautiful finish in even the most crappy junk yard steel I use.

Andre3127
10-28-2016, 01:00 PM
Oh no, I don't mean to dis the leatherman diamond file. They have two kinds of diamond file, one very fine and a coarser one used on some other tools. The finer one I have is excellent, I use it for all sorts of things. It removes carbide very fast, it's keeping a consistent angle that is the hard part. One of these days I'll pick up a cheap diamond wheel and put it on a slow speed motor I have.

Thanks for the carbide info Matt, I'll check them out!

mattthemuppet
10-28-2016, 03:10 PM
you're welcome!

Andre3127
10-28-2016, 06:16 PM
Well, I ground up a standard profile turning tool (right hand roughing in the diagram) and can take .070" per side no problem, and probably more but I didn't sharpen the leading edge far back enough to try a .1" per side pass. I did not use any top rake, but the chips are forming nicely and are not turning bronze color.

http://web.mit.edu/2.670/www/Tutorials/Machining/lathe/cuttools.gif

DR
10-28-2016, 09:38 PM
Nothing in the way of wear or breakage would surprise me about brazed carbide tools.

Brazed tools generally are not a mainline, quality product anymore. The low end stuff which I presume most here would be buying are crap.

Back in the pre-insert days a brazed tool might have been a quality item, but that time has passed.