Grizzly G0602 Lathe Rough Finish

[TWS]

Hello,
I am new to the Hobby Machinist and sure need some advice.
I bought a Grizzly G0602 Lathe 10x20 with the workbench for mounting.
Everything went great with the break in and leveling and i was making chips with a great finish using carbide and HSS, mostly cutting 1018.
I decided to switch out the tool post to a quick change. I milled the t nut for a nice tight fit and installed it. Centered my tool and went to cutting. The finish got really rough, either tiny lines evenly spaced or a smearing of the metal using both carbide and HSS.
I figured something was wrong with the tool post so I switched back to the original tool post to test the idea. Same issue, rough and lines.
What happened it cut great for 3 months then this rough finish. When i hold up a piece I had worked on before the issue on the same 1018 stock and compare it it is hard to believe how horrible it got.
I check gearing, belt tension, level, checked the four jaw chuck for tightness, adjusted the jib a little tighter, tried different feeds and speeds and different tooling, carbide and HSS. Nothing makes it better.
To change speeds i have to loosen the motor mounts to put the larger belt on the high speed pulleys. I checked the mounts for tightness and they are torqued down tight.
So what did i do between my nice finishes and this rough garbage.
I put a four jaw chuck on (but it cut fine afterward)
I changed gearing so i could cut some threads (i check the backlash and it seems fine)
I changed belts from low to high and back
I changed to a QCTP (seemed to get bad then) but i changed back to the original post which had a spring loaded dowel and set screws in the t nut, this did not help.
The runout on the chuck seems fine and I dial in my work to .0005 before i cut.
I am at a loss, i did order some other steel that is supposed to cut cleaner but I had been cutting 1018 for months with a decent finish.
Anybody out there have a Grizzly or experienced this issue before?
I would would appreciate you comments.

 

[WobblyHand]

Have you checked your tool height? For a quick check, use a metal scale and gently sandwich it in between the cutter tip and the work piece. The scale will be vertical if the cutter tip is at the correct height. Adjust the tool height until vertical and try another cut.

Is your insert good? Look at it under a magnifying glass for any chips in the insert. Run your fingernail on the edge, if it hangs anywhere it is probably chipped. Rotate the insert to access a new cutting edge. Try another cut.

Examine your compound, and new tee nut. Is the surface of the tee nut below the compound? The tee nut must be below the surface of the compound.

The above are not the only possible things that could go wrong, but the ones that come to mind right away.

1018 is known for poor finishes. Try some aluminum (6061) or 12L14 steel or 1144 steel, all give nice finishes.

I have a Grizzly G0752Z which is just a G0602 with a couple of extra things. I was using mine this afternoon with a QCTP tool post. I get good finishes on machinable steel and aluminum. Not as good of a finish on 1018. Here's a little gyroscope that I was working on today.

The wheel is made of cast iron, the ring out of 6061 aluminum, the shaft out of 1144 steel, and the end pieces out of 360 brass. All done on a QCTP on a G0602 equivalent lathe. 10 x 22.

 

[Huub Buis]

The first cause would be less rigidity. Your QCTP probably has more overhang and the stickout of the tool in the QCTP probably is longer.
The flex increases (power of 3) when the length increases.

The second could be the adjustment of the gibs. Just tighten the gibs pretty strong and turn using the power feed.

 

[TWS]

Have you checked your tool height? For a quick check, use a metal scale and gently sandwich it in between the cutter tip and the work piece. The scale will be vertical if the cutter tip is at the correct height. Adjust the tool height until vertical and try another cut.

Is your insert good? Look at it under a magnifying glass for any chips in the insert. Run your fingernail on the edge, if it hangs anywhere it is probably chipped. Rotate the insert to access a new cutting edge. Try another cut.

Examine your compound, and new tee nut. Is the surface of the tee nut below the compound? The tee nut must be below the surface of the compound.

The above are not the only possible things that could go wrong, but the ones that come to mind right away.

1018 is known for poor finishes. Try some aluminum (6061) or 12L14 steel or 1144 steel, all give nice finishes.

I have a Grizzly G0752Z which is just a G0602 with a couple of extra things. I was using mine this afternoon with a QCTP tool post. I get good finishes on machinable steel and aluminum. Not as good of a finish on 1018. Here's a little gyroscope that I was working on today.
View attachment 429197
The wheel is made of cast iron, the ring out of 6061 aluminum, the shaft out of 1144 steel, and the end pieces out of 360 brass. All done on a QCTP on a G0602 equivalent lathe. 10 x 22.

I did check tool height (forgot to mention that).
THe insert is good, when i first got a bad finish I changed it and since i have used several different inserts to see if I could get a better finish. I use good inserts (I think) MItsubishi and ISCAR.
The tee nut is below the compound.
I will be trying some different steel soon and thank you for your input and advice.

 

[TWS]

The first cause would be less rigidity. Your QCTP probably has more overhang and the stickout of the tool in the QCTP probably is longer.
The flex increases (power of 3) when the length increases.

The second could be the adjustment of the gibs. Just tighten the gibs pretty strong and turn using the power feed.

Your right there is a bit more stickout but not a great amount. 3/4 inch but times 3 makes it worse. I am using 1/2 insert holders.
I will try to adjust the jibs again and use the power feed. (i mostly have been doing it by hand) I will report back when i do it and finish the test.
Thank you so much for your input as i am at a loss.

 

[TWS]

Have you checked your tool height? For a quick check, use a metal scale and gently sandwich it in between the cutter tip and the work piece. The scale will be vertical if the cutter tip is at the correct height. Adjust the tool height until vertical and try another cut.

Is your insert good? Look at it under a magnifying glass for any chips in the insert. Run your fingernail on the edge, if it hangs anywhere it is probably chipped. Rotate the insert to access a new cutting edge. Try another cut.

Examine your compound, and new tee nut. Is the surface of the tee nut below the compound? The tee nut must be below the surface of the compound.

The above are not the only possible things that could go wrong, but the ones that come to mind right away.

1018 is known for poor finishes. Try some aluminum (6061) or 12L14 steel or 1144 steel, all give nice finishes.

I have a Grizzly G0752Z which is just a G0602 with a couple of extra things. I was using mine this afternoon with a QCTP tool post. I get good finishes on machinable steel and aluminum. Not as good of a finish on 1018. Here's a little gyroscope that I was working on today.
View attachment 429197
The wheel is made of cast iron, the ring out of 6061 aluminum, the shaft out of 1144 steel, and the end pieces out of 360 brass. All done on a QCTP on a G0602 equivalent lathe. 10 x 22.

That is a nice piece you made. Finish look good. Pretty cool.

 

[WobblyHand]

For what it is worth, I mostly use 3/8" tooling. It seems to be rigid enough. I don't take huge cuts though. I'm not in a hurry.

What was your depth of cut when the finish started looking poor? What inserts were you using?

Here is something else that could cause a bit of a problem. Check the threads in your tee nut. Are they raised upwards above the surface? Like a bur? This can prevent the tool post from fully seating on the compound. And that can makes things less rigid.

Also, is the compound clamp down tight? The stock compound clamp is a bit wimpy. I had problems with mine and made a new one. Here is a picture of the stock and new compound clamp. The new one really holds the compound down.

 

[homebrewed]

Are you manually advancing the cutting tool or using the lathe's fine feed capability?

Comments about chips getting into undesired places are spot on, they have a way of finding the worst-possible place to come to rest. And they can be hard to find -- it doesn't take much to mess up the rigidity of your setup.

Problems like yours can be difficult. You changed something, going from the original tool holder to a QCTP; then the finish degraded and didn't recover when you _apparently_ went back to the original setup. Maybe you didn't completely do that -- perhaps left a different mounting stud in place, maybe something else. Maybe you dropped something on your concrete floor. Reconstruct the "scene of the crime", as best you can.

Or it could be something unrelated that decided to go south at the same time. It's been known to happen!

 

[TWS]

For what it is worth, I mostly use 3/8" tooling. It seems to be rigid enough. I don't take huge cuts though. I'm not in a hurry.

What was your depth of cut when the finish started looking poor? What inserts were you using?

Here is something else that could cause a bit of a problem. Check the threads in your tee nut. Are they raised upwards above the surface? Like a bur? This can prevent the tool post from fully seating on the compound. And that can makes things less rigid.

Also, is the compound clamp down tight? The stock compound clamp is a bit wimpy. I had problems with mine and made a new one. Here is a picture of the stock and new compound clamp. The new one really holds the compound down.
View attachment 429200View attachment 429201

Depth of cut is usually .005 or .0025, deeper cuts get much worse finish.
I will check the T nut
I really like you compound clamp, pretty slick.
Thanks for your input

 

[WobblyHand]

Depth of cut is usually .005 or .0025, deeper cuts get much worse finish.
I will check the T nut
I really like you compound clamp, pretty slick.
Thanks for your input

Not my idea. Found it on HM. However, here's my thread on it, with full accreditation.

G0602/G0752Z Compound Clamp

Looking at the backlog of projects, decided to do this one next. This design is copied from @RJSakowski. Looks like: With RJ's permission (a while ago) I posted the FreeCAD file in Downloads. So if you want the file, download it from there. Started out with a piece of 1x4 A36 steel. Took...

www.hobby-machinist.com

FreeCAD model is uploaded to the HM download area.

If you are having issues with that small of a cut, there's a problem. Something like a tee nut bur, or something else is loose somewhere. Have you checked the tightness of the saddle tension clamp 222 in the back of the saddle? Or the more obvious slide block 917 in the front of the saddle? Saddle gibs? Compound rest gib? Is screw 208 tool post bolt seated into the tee-nut? There's not that many places it can be...