What am I doing wrong

[francist]

Paul, you're getting lots of pointers not the least of which is that burned (torch cut) edge. They can be real bothers to get through. Before you even think about taking very heavy cuts though I would take a close look at your compound slide. It's extended quite far out to end of its travel. This is very precarious, and on the 6" lathe like you have the compound slide is not robust to say the least. You really run the risk of breaking it with heavy and/or interrupted cuts when it is extended that far out. Please don't let it to end up like this one...



-frank

 

[GK1918]

Yes nasty; I would throw the thing in a charcol pit. the ole Henry Ford Kingsford stuff.
go home tomorrow will be a different day. Then what I do is not chuck it but drive it
between centers with two way tape anything. cover lathe, turn lathe on and lightly
grind the torch cuts, then proceed to turn down. And I say cover lathe beds. I hate any
kind of grinding on any of my lathes but sometimes ya have to ..damp rags work too.

 

[neshkoro]

I agree. The compound is cranked way to much to the left. Crank it back until the tool holder is supported by the gibs/ ways. Carbide is the way to go with that flame cut material. At least until you get past the hardened part. Good luck.


Sent from my iPhone using Tapatalk

 

[Wreck™Wreck]

I hate to ask but is the spindle turning in the correct direction for the tool? Last year I set up a lathe job for someone else to run, ran a few while he watched (1400 total parts) then went to another machine.
10-20 minutes go by and he comes over and tells me that the insert broke, I have a look and can't see any reason why, checked the offsets and they were fine so finally asked him to show me what he did and sure enough he turned the spindle on in the wrong direction. I managed to stop it before he hit the start button.

Another guy I know from the local Tavern asked me about his wood lathe problem, said it wouldn't cut, asked him which direction it was turning, he spun a finger in the air, wrong direction of course so I told him it wouldn't cut that way but is surely safer (-:

Turned this lovely beast this past Friday, 500 FPM with a CNMG insert without a problem.
24 1/2" OD at 80 Rpms. .008" IPR feed.

 

[azshadeguy]

Disc appears to be torch cut. If so you may need to grind to the heat affects hard edge before attempting to turn.
Good luck.
Dave

.
Yes they are torch cut I will grind them

Is that a good quality tool you are using? Also with a large workpiece the surface feet per minute will be high at the outer edge so use a slow enough
spindle speed and some cutting oil- carbide tools are great for that flame-cut stuff
Mark S.

These are cheap tools off ebay
http://www.ebay.com/itm/5pc-3-16-x-...e=STRK:MEBIDX:IT&_trksid=p2060353.m2749.l2649
where do you get carbide in a 3/16 cutter?

 

[azshadeguy]

What spindle speed are you turning at? A rough surface like that should be turned very slowly until it cleans up... also, being torch cut, it may be a lot harder on the edge than in the center.

It may help to slow it down and, starting at the edge, feed toward the center until it cleans up, back out, move to the left .010 thousandths, then feed back toward the center... repeat.

In other words, rather than feeding across the cut edge, feed into the cut edge... being sure not to cut past your finish diameter of course. When you get the edge cleaned up, it should cut easier.

Also, I can't tell for sure in the pics, but it looks like you may have too much relief below your cutting edge, making the edge weak. For an interrupted cut, you need just enough relief to prevent 'rubbing' the workpiece.

-Bear

I will re grind the tool and slow it down

I agree. The compound is cranked way to much to the left. Crank it back until the tool holder is supported by the gibs/ ways. Carbide is the way to go with that flame cut material. At least until you get past the hardened part. Good luck.

I will pull it in

 

[azshadeguy]

I hate to ask but is the spindle turning in the correct direction for the tool? Last year I set up a lathe job for someone else to run, ran a few while he watched (1400 total parts) then went to another machine.
10-20 minutes go by and he comes over and tells me that the insert broke, I have a look and can't see any reason why, checked the offsets and they were fine so finally asked him to show me what he did and sure enough he turned the spindle on in the wrong direction. I managed to stop it before he hit the start button.

Another guy I know from the local Tavern asked me about his wood lathe problem, said it wouldn't cut, asked him which direction it was turning, he spun a finger in the air, wrong direction of course so I told him it wouldn't cut that way but is surely safer (-:

Which way should it be turning? so looking at the part it is going counterclockwise

 

[neshkoro]

If you have a mill you could cut down a 3/8" brazen carbide tool.


Sent from my iPhone using Tapatalk

 

[neshkoro]

Brazed!


Sent from my iPhone using Tapatalk

 

[Wreck™Wreck]

Which way should it be turning? so looking at the part it is going counterclockwise

The surface of the part moves towards the cutting side of the tool, CCW when facing the spindle when the cutting face of the tool is facing "up" on the operator side of the part, otherwise known as the front.

It is entirely possible that the tool that you ground is dragging a non cutting surface on the work, this may be caused by the cutting edge being well above the centerline of the spindle. Place a center in the tailstock and run the tool tip to the point of the center, if it is well above the center point this is your problem. Otherwise examine the tool closely as the point of contact with the work will leave a mark on it revealing the problem.