Having trouble after QCTP install.

I am turning down 1.25" mild steel rod (cold roll?)
The tool bits are both HSS and carbide
The speeds I have tried are 350-700 RPM my feed is set to .011? and the DOC has varried but .002 to .0010
I have tried several tools, made new ETC with no luck. I thought the same thing.

for a 1.25" dia. piece of mild steel and a HSS tool bit I'd run it about 240 rpm (that's 80 sfpm).

if you don't know that you have the original pulleys (and therefore the original speed ranges) a cheap laser tachometer like this is great:
http://www.ebay.ca/itm/New-Handheld...675837?hash=item3d30db2efd:g:VakAAOSwEK9Tsh1f

I used one and made a chart of speeds with and without back-gear, laminated it and leave it at the lathe.

-brino
 
Cheap tach...

Fetch a chunk of all thread and place it in the chuck.

Avoid stainless...

Finer is better and have stick out an exact inch...2, 3 and first use wire wheel to be sure no burrs and get a not that fits it.

Chase threads if needed so it spins on the all thread.

Place nut against chuck and run lathe in REVERSE

Grab nut with pliers and have helper time it so see how long it takes for nut to come off.

Then math...

Threads per inch so you know how many rounds in the time it took to come off so easy to determine rpm.

Very crude but it works.

Old school tool was a worm gear device you placed against rotating shaft for a measured time and the dial rotated to indicate rounds so this is home made version of old school tool...

Sent from my SAMSUNG-SGH-I337Z using Tapatalk
 
OK more progress made. I believe my biggest issue was SPEED, pure and simple RPMs. I recently got the dual speed pulley bushed up and installed correctly and I have determined that the slower speed there and the bottom 2 speeds on the flat belt work the best for the steel I am cutting. I can speed up to the highest flat belt speed when I done and take a "polishing" cut and its fine. I may or may not have the correct motor pulley, but I can tell now that for most of the things I want to have the ability to do low speed will be used. I do wonder how I am going to use the live center when I have to work close to it with this new tool post. It seems as tho I will have to allow the cutting tool to protrude more that I am currently doing, although I may be overdoing it with my closeness to the toolpost. How far out is too far out? I really need a machinery's handbook, how much better is the new one vs an older copy?

Thanks again for all the help!

Jason

Jason,

To answer your questions in reverse order, I have a 12th edition and two 21st editions. I don't know what the current edition is up to now but would expect it to have at least some stuff that just doesn't apply to your older manual machine. So from personal experience, I can say pretty much any edition between 12 and 21 should be fine for use with your lathe.

I assume that you have an AXA size QCTP. The 101 or 102 holders that are the most commonly used have four set screws. In most of mine, I have two 3/8" square cutters mounted, one usable for turning and one for facing. Except that in one, I have a 90 deg, "V" cutter mounted (in place of a facing one) that I use for routine beveling and chamferring. They are all arranged such that each cutter occupies one half of the slot. I would say that is the minimum (or maximum extension). For working near the live center, what I do is rotate the TP 90 deg. CW, mount the turning cutter as though it were going to be used for facing, and hang it on the right side of the TP. That usually gives adequate clearance unless the part diameter is very small. In that case, you can use something like an AL6 brazed carbide cutter and work toward the tailstock instead of toward the headstock.

On cutting speeds, your first step should be to determine what speeds your machine actually does with the pulleys that you have. Make a speed chart for the machine. Then in whatever edition of Machinery's Handbook you acquire, find the tables of recommended cutting speeds versus materials. And the cross-reference table from surface speed to RPM at different diameters. In the 21st Edition, the speeds versus materials charts start on page 1759. And the RPM tables on 1790. Note that you can usually safely use the HSS figures with carbide cutters but not vice versa. Also, most of the entries give surface speeds for two or more hardness ranges. If you don't know the hardness, start with the speed for the hardest which will be the slowest. If that works OK, try your next faster speed and so on until it doesn't work so well, and then slow back down a notch.

But don't get stuck on using the same RPM on all diameters of the same material just because its that material. The best RPM for turning a 1/2" diameter steel rod will be much too fast for 2".
 
The gib should be held parallel by the bolts. It's been a while since I had one apart but I don't remember any spacers. Guess I should scroll back and look at the parts breakdown. What model lathe is it?
Ok...I stand corrected. I see the spacers.
 
Only on the front.
 
Back to the oil. Find an oil supplier, not auto but ISO 68. It will be non-detergent. It may be easier to go the hardware store (Ace) and get a squeeze bottle of appliance oil. It is also 20w. The bottle will have an extension tube that pulls out to extend the reach. It is NOT 3in1 oil. A little not cost per qt. but readily available. Mine lasts a year and a half.
 
Actually, in Houston the only cans of oil actually marked SAE 20 are packaged by 3 in 1. :) But you have to look carefully to spot the difference. And it would be quite expensive if you use your equipment very much.
 
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