Advantage to Rear mount cutoff 3018 vs 3016 rearmount spacer block?

Aaron_W

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I have the standard front mount cutoff tool (3002) that came with my lathe. I understand the potential advantages of the rear mount but wondering if there is any reason to get the dedicated rear mount cut off tool (3018) vs the rear mount spacer block (3016) that converts the front mount cutoff tool to a rear mount.
I can't imagine there are that many situations require both a front and rear mount tool at the same time, and other than the spacer block potentially being a little less solid, it seems like the spacer block would be preferred for the added flexibility and being cheaper if one already has the front mount cutter.

Any flaws in this logic?
 
Do yourself a big favor and make your own rear mounted parting tool post. Each lathe has its own spindle centerline and this determines how well the tool cuts. This is a simple project that a new guy can do. If you need guidance, PM me.
 
what Mike said! Rear cutoff works great on my Sherline!
 
Someone should post a picture of there rear mount parting tool because I'm sure it would be a good reference for others.
 
Sure, here you go:

IMG_5298.JPGIMG_5300.JPGIMG_5303.JPG

The cutting edge is on the exact centerline of the lathe spindle. Top two screws hold the blade in place. The center screw holds the post to the bed with a t-nut. The ledge registers on the edge of the cross slide so the tool cannot move. Parts with no issues at all.
 
I'm planning on doing this also. I have a Phase II piston type QCTP that I'm not using and thinking about integrating that into the rear mount. Will probably be mounted on a 2024 aluminum block. Not sure how I'm going to mount the block on my cross slide, whether I tap or drill and use a nut on the bottom.
 
I still haven't got used to the idea that I can make stuff...

Mikey, I'm still in the midst of rearranging a new shop. The addition of the mill and grinder has caused some adjustment. Once I'm set up I will follow up on your offer. It probably seems easy, but I will need some help finding the right height for the cutting tool.
 
It probably seems easy, but I will need some help finding the right height for the cutting tool.
Chuck up a piece of rod and face it. The middle of the bullseye on the face of the work is the correct height.
 
Re: Rear mount cutting tool, I went to the trouble of making a new cross slide base for my Atlas Clausing MK2 620 lathe. put a rear mount cut off tool on it. It worked fine until it somehow jammed and lifted the back of the cross slide about an inch. The problem could be the plastic gib on the cross slide. I've been thinking about making a bronze gib to take it's place, haven't done it yet .
 
I still haven't got used to the idea that I can make stuff...

Mikey, I'm still in the midst of rearranging a new shop. The addition of the mill and grinder has caused some adjustment. Once I'm set up I will follow up on your offer. It probably seems easy, but I will need some help finding the right height for the cutting tool.

Yeah, let me know when you're ready.

It is critical that the point of the parting tool be on the exact centerline of the lathe, and every lathe is different. If it is too high, it won't cut. If it is too low the tool can dig.

The best way to get center height is to turn a piece of something - steel, aluminum, brass. Turn to get a consistent diameter and finish, then measure the distance from the mounting surface where your parting tool post will sit to the top of the rod you turned. Be as concise in this measurement as possible; I use a height gauge. Then measure the OD of the turned piece, subtract 1/2 that OD from the height gauge measurement and you have your spindle centerline.

A rear mounted parting tool is used upside down. The bottom of the slot that holds the parting tool must be at the distance you found in the step above. You cannot be above that measurement but you can be below by maybe a thou or so but try to get it exactly right. A sharp tool positioned this way will not dig, chatter or do anything else but cut.
 
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