Internal Key-way Shaping

[Nigel Graham 2Participant @nigelgraham2]

HOORAY! I have found the missing book – hence found what had confused me.

It is Ian Bradley's Shaping Machine & Lathe Tools (MAP Technical Publication, Argus Books Ltd., 1976).

Bradley describes the geometry of spring-shank tools and how they can dig in, but interestingly does not say anything about the relationship of tool-tip to clapper-box pin. Instead, the tip should be slightly behind the line of support, so the tool will tend to lift rather than dig in more tightly.

So I obtained the mantra of relating tool-tip to fulcrum from some other book, or an article in ME perhaps, but have not managed to trace it. It seems the key is to go by the vertical face supporting the tool, instead.

On a big, very rigid industrial shaper or planer the chances of the tool digging-in are far less of course, unless by operator error or clumsiness – but that's workman not tool.

He gives a set of drawings for the general-purpose tool-holder, saying his was for a Drummond manual shaper (same as mine) – the prototype was a cycle crank but that's not important!

Dealing with the original point, Ian Bradley does show internal slotting needs the tool drawing back to cut, with the clapper-box locked, but I want an alternative to his suggested bar screwed to the ram-head jaws.

The clapper-box is also locked when cutting T-slot sides or other operations in which letting the tool swing back would cause it to jam.

Intriguingly, the author also shows the basic way to cut pinion teeth (rough out with a square tool first), and recounts having once used an old thread-chaser to shape swathes of diagonal grooves to produce tread-plate for a model loco's footplate. It would produce a raised-lozenge pattern, for which an effective de-burring tool might be a rotary wire brush in a power tool.

The shaper's natural finish would of course also be right, with appropriate tool-profile and feed, for model parts whose full-size counterparts would have been left with shaped or planed surfaces.

++++

My club used to own a massively-built but quite basic shaper, driven by a 3ph 3HP motor as I recollect. Its ram-head was topped by a quadrant engaging a worm operated by a small handle on its end, and although it put the operator rather horribly close to big hungry lumps of moving iron, it could be used for shaping concaves. We used it to make the fabricated, steel smoke-box saddle, of about 3.5 in radius, for the club-project loco, a 7.25in g. version of LBSC's Juliet.

[IanTParticipant @iant]

Posted by Nigel Graham 2 on 04/12/2020 22:07:57:

On a big, very rigid industrial shaper or planer the chances of the tool digging-in are far less of course, unless by operator error or clumsiness – but that's workman not tool.

No Nigel, quite the opposite – tool "dig-ins" are not a function of how solid or large the Shaper is – but more how flexible the "tool" (or its holder) is relative to the forces being applied. The fulcrum point is not the clapper pin, it's the point where the 'tool' is no longer fully supported by the mass of the arm and its clapper box. The more the 'tool' is extended, the more likely it is to flex (because of leverage effects) – so if you minimise any extension of the tool – then "dig-ins" (e,g. chatter) are less likely to occur.

But sometimes, you do need to over-extend the tool (regardless of machine size) – so placing the cutting edge behind the 'flex' point results in the tool being lifted (rather than dug-in) should the tool or holder flex…

Regards,

IanT

[John OlsenParticipant @johnolsen79199]

Here are a couple of commercial shaper tools. One is very like the usual Jones and Shipman type, except if you look carefully you will see that it does not have the built in top rake that is common with lathe versions. The other is what the bicycle crank type is modelled on. The tool bit can be set vertical, at 45 degrees either way, or at 90 degrees either way. The disadvantage of this type is that the tool bit must be long enough to reach right across the inside, so it can't be used once the bit is getting shorter. The one in it is sticking out a bit far , because it can't go any further back in the slot in the fixed piece and I did not want to cut about half an inch off the end to make it shorter. It works fine like that, and as it gets sharpened it will end up with less and less overhang. If you decide to make one, use a steel crank!

The potential problem is not to do with the clapper pivot, it is bending in the tool causing a dig in. I have really only had problems with slotting blades trying to dig in, this is much the same problem as the difficulties with parting off in a lathe.

I've made special tooling to help with doing inside keyways a couple of times, but usually don't bother and do it the drill and file way. This is mainly because it takes longer to arrange tooling than it does to do the keyway, so unless you want to do a lot the same, why bother. One idea uses a piece like a cotton reel split lengthways with flanges on the end to suit the job. The flanges on one end are mostly removed so that the two pieces can be wangled inside the hole in the job, leaving a slot between them just the width of the desired keyway. This guides the cutting tool, made from flat the right thickness, so that the end cannot wobble sideways as it cuts the keyway. This works very well, although it makes it hard to see what is going on inside the job.

John

[John HaineParticipant @johnhaine32865]

Posted by John Haine on 02/12/2020 10:51:49:

**LINK**

Edited By JasonB on 02/12/2020 11:03:23

Frankly, this is getting stupid. Hopper asked if a slotting attachment could use a motorised drive, I posted a link to show that such things were easily available from eBay as an example, then the link gets removed. This so-called code of conduct is rapidly making this site unusable.

[Nigel Graham 2Participant @nigelgraham2]

Ian –

I think Ian Bradley's point was that on a large machine using larger section tools, the tool can't spring anyway.

He does make clear that the tool flexes about the lower edge of its support, nothing to do with the clapper-box action. I repeated that point.

My original comment about setting the cutting edge behind the clapper-box fulcrum came from other sources probably basing the advice on using rigid tools on fairly light machines. Of course, they might have been wrong!

The Bradley book was published in the 1970s, and seems to reflect a time when forged spring tools, for lathes as well as shapers, were still widespread in model engineering, but rigid HSS bar and even carbide-tipped tools were becoming more common.

John –

Thank you for that additional information. I think you've identified for me the nature of a large tool-holder in my possession – but if it was for a shaping- or planing- machine, it was a big machine! I believe I also have a J&S holder similar to yours and if I can find it I will examine it more closely. I normally use QCTPs on both my Myford and Harrison lathes.

I like the principle of the key-way centering guide. I'd assumed using a full-diameter bar in place of the cutter-holder itself as a centring aid, but not thought of keeping the cutting-tool on the straight and narrow like that.

I know someone who used the principle a stage further to make internal splines on a gear, by welding or brazing a slotted cylinder inside the bore.

[not done it yetParticipant @notdoneityet]

Posted by John Haine on 05/12/2020 09:32:38:Posted by John Haine on 02/12/2020 10:51:49:

**LINK**

Edited By JasonB on 02/12/2020 11:03:23

Frankly, this is getting stupid. Hopper asked if a slotting attachment could use a motorised drive, I posted a link to show that such things were easily available from eBay as an example, then the link gets removed. This so-called code of conduct is rapidly making this site unusable.

The easy way is:

The answer to Hopper’s post is “yes’. Instead of falling foul of the CoP, why not send a link by PM. Totally removes the need for a post such as above, if one uses one’s head imagination. I’m not even sure that Hopper’s post was anything more than rhetorical, so was not really asking for any direct link.

[JasonBModerator @jasonb]

Posted by John Haine on 05/12/2020 09:32:38:

Posted by John Haine on 02/12/2020 10:51:49:

**LINK**

Edited By JasonB on 02/12/2020 11:03:23

Frankly, this is getting stupid. Hopper asked if a slotting attachment could use a motorised drive, I posted a link to show that such things were easily available from eBay as an example, then the link gets removed. This so-called code of conduct is rapidly making this site unusable.

Could you not simply have said "look at linear actuators" ?

[Michael GilliganParticipant @michaelgilligan61133]

Posted by John Haine on 05/12/2020 09:32:38:

Frankly, this is getting stupid. […]

.

… especially when the harsh reality of [presumed] compliance with safety standards is so clearly demonstrated in Bob Stevenson’s recent post : **LINK**

https://www.model-engineer.co.uk/forums/postings.asp?th=169503&p=1

MichaelG.

[HopperParticipant @hopper]

Posted by not done it yet on 05/12/2020 09:57:03:

Posted by John Haine on 05/12/2020 09:32:38:Posted by John Haine on 02/12/2020 10:51:49:

**LINK**

Edited By JasonB on 02/12/2020 11:03:23

Frankly, this is getting stupid. Hopper asked if a slotting attachment could use a motorised drive, I posted a link to show that such things were easily available from eBay as an example, then the link gets removed. This so-called code of conduct is rapidly making this site unusable.

The easy way is:

The answer to Hopper’s post is “yes’. Instead of falling foul of the CoP, why not send a link by PM. Totally removes the need for a post such as above, if one uses one’s head imagination. I’m not even sure that Hopper’s post was anything more than rhetorical, so was not really asking for any direct link.a

Actually I was trying to find which of the millions of automation drives now available would suit. So a direct link to exactly what I needed would have been right handy. Not being allowed to post it is just ludicrous. It's not a product that competes with any of this site's supporting advertisers, which is the ultimate driver of that section of the CoC about links to competing and/or cheaper overseas sources.

At least the mystery of that post is revealed. I thought John Haines was pointing me at the CoC because he was not happy with something I said, which was totally confusing. John, thanks for trying to help. Guess I'll trawl through the millions of listings on eBay and Aliexpress and find something that I might guess you were trying to do me the favour of pointing me toward. Since I saw that video I posted, I'm keen to make something with a more modern automated drive.

[HopperParticipant @hopper]

Posted by Michael Gilligan on 05/12/2020 10:21:57:

Posted by John Haine on 05/12/2020 09:32:38:

 

Frankly, this is getting stupid. […]

.

… especially when the harsh reality of [presumed] compliance with safety standards is so clearly demonstrated in Bob Stevenson’s recent post : **LINK**

https://www.model-engineer.co.uk/forums/postings.asp?th=169503&p=1

MichaelG.

Indeed. Very poor. The CE markings really don't mean much at all in cases like that.

And the harsh reality of presumed consumer protection when dealing with UK suppliers is clear in the second last post on this recent thread LINK

 

 

 

Edited By Hopper on 05/12/2020 10:41:08

Edited By Hopper on 05/12/2020 10:42:03

[HopperParticipant @hopper]

Posted by JasonB on 05/12/2020 10:06:30:

Posted by John Haine on 05/12/2020 09:32:38:

Posted by John Haine on 02/12/2020 10:51:49:

**LINK**

Edited By JasonB on 02/12/2020 11:03:23

Frankly, this is getting stupid. Hopper asked if a slotting attachment could use a motorised drive, I posted a link to show that such things were easily available from eBay as an example, then the link gets removed. This so-called code of conduct is rapidly making this site unusable.

Could you not simply have said "look at linear actuators" ?

I tried doing that, twice on other threads, to recommend an international sales website and the search term to use to find electric motor/speed controllers that members were seeking information on. Both posts were entirely deleted without even the courtesy of an explanation.

That was despite no links having been posted and thus posts complied with the Code of Conduct, which only proscribes "links" and "linking", not naming or describing.

If we are no longer allowed to even discuss, or name, unapproved websites or post the description of the item that might help a fellow forum member out, then the Code of Conduct should be amended to say that.

Otherwise, mods should stick to the existing Code of Conduct that proscribes links only.

[JasonBModerator @jasonb]

Hopper mentioning the site several times in your post and posting a big bold copied and pasted full description of the item is as good as posting a link as far as I see it. If you have a problem suggest you contact Neil.

Edited By JasonB on 06/12/2020 12:05:49

[HopperParticipant @hopper]

This site has no way for me to make the lettering smaller and I was on my phone so cutting and pasting and leaving as is was the easiest option for me. No cause for pettiness IMHO.

 

 

Edited By Hopper on 06/12/2020 12:19:09

[Author]

Posts