TAPER TURNING ATTACHMENT ON A HARRISON M300

Can anyone explain how the Harrison m300 taper turning attachment overcomes the cross slide nut

to cut the taper I understand the sliding section on the end of the screw

but what is the gear for on the end of it? is this driven by something?

Hugh

Looking at the parts book I guess you are referring to the gear at the dial end made on the part that also carries socket that the sliding section of the screw fits into. This gear is driven from the apron to provide power cross-feed.

When using the taper turning attachment the cross slide is moved via the, now stationary, nut and screw whilst the dial and power feed gear stay fixed in the apron. The sliding section allows the screw to effectively change length thus accommodating any variation. Many lathes don't have a such a sliding section so the dial and handle assembly has to be released from the screw to let things move. Alternatively the taper turning attachment can be made to connect directly to the cross slide so the feed nut has to be similarly disconnected to let the slide move independently of the screw. High end toolroom lathes and the like sometimes have a second cross slide underneath the normal one to which the taper turning unit can be connected rendering its operation completely independent of the normal cross slide. very effective but expensive.

As taper turning units are often rarely used and even less likely to be operated over their full travel crud and stuff can build up in the end of the socket restricting the range of travel. A nasty surprise if discovered near the end of an accurate and hard to set up job. If you are doing a retrofit best to clean up and verify full travel before installation. Otherwise something to add to the service schedule. On the 10 year list I think. I found that one out the hard way with my SouthBend Heavy 10. Even worse in that case as the keyway hadn't been fully machined needing some careful file work to get it to full length and dead on size. Job was a do-over too.

Its important to get the gibs and sides set-up really nicely for smooth shake-free and easy movement. Uneven drag can easily upset the taper you are making. Another thing I learned from that SouthBend. Ended up taking the whole unit off and doing a very careful set-up job on the bench. Impossible to see and feel what was going on well enough to get it just so whilst leaning over the machine. Probably fine to do it on the lathe if you have rear access but who in the ME world has that much room. Worth the effort as good Morse tapers and the like could be made with no fiddling beyond the usual extra care needed to set-up.

Clive.

Thanks Clive for your very comprehensive reply.

No I was referring to the gear on the end of the sliding section of the taper turning attachment. As far as I am aware there is no gear on the apron to drive this gear and due to the socket on the other end it would be positioned within the cover of the taper turning attachment. The tool post is fixed to the cross slide the cross slide is fixed to the apron the cross slide can not be moved unless the cross slide dial is turned, is this driven by some means is my query.

thank you for your help

Hugh

Hugh

That doesn't sound right. Looking at the Manual / Parts book drawing 312, page 59 of my download version, the only gear is the one I mentioned made as part of the dial carrier shaft part no 312.033.

With a system of this type if the cross slide can only be moved by turning the dial or via the power feed it suggests that a solid feed screw has been fitted instead of the telescopically jointed one.

Do the parts on your lathe not correspond to the manual? If you don't have a manual this link for a download should work :- **LINK** .

Clive

Edited By Clive Foster on 02/04/2017 15:31:57

Hello Clive

Thanks for all your help. It all becomes clear I was assuming the part shown in the exploded views was an additional

part and not a replacement for the existing part within the saddle assembly. The reason I was asking the question

was because I am looking to purchase one and I wasn't sure if it was all there, but I now see that it is.

Hugh

Hi all

I recently borrowed one of these TTA's and wrote up some notes. I've created a post "Harrison Taper Turning Attachment for M250/300" in the "Workshop tools & tooling" forum. Hope it helps.

Chris