Tangential tooling, from first principles

[Michael GilliganParticipant @michaelgilligan61133]

This is less than 11 minutes, and quite educational:

https://youtu.be/oPgx9P6Jn_s?feature=shared

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MichaelG.

[Sonic EscapeParticipant @sonicescape38234]

l also want a tangential cutter but so far I couldn’t decide if to order one or to try to make it myself.

[Thor 🇳🇴Participant @thor]

Not difficult to make, I have made two, one for my small lathe and another for my slightly larger lathe. The are use a lot.

https://b56b541582.cbaul-cdnwnd.com/15a4602be4074f1b8217350ccf583f6b/200000026-83350852aa/TangToolholder.pdf

Thor

[John HaineParticipant @johnhaine32865]

In the “old” forum somewhere I posted how to calculate the grinding angles to get a required top rake given the fixed “lean” of the tool given by the holder.  However the site search can’t find it!

[John Haine]

On John Haine Said:

In the “old” forum somewhere I posted how to calculate the grinding angles to get a required top rake given the fixed “lean” of the tool given by the holder.  However the site search can’t find it!

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John is clearly correct, on both counts … the **LINK** returns the dreaded LEGO blocks.

MichaelG.

[VicParticipant @vic]

They are easy to make, this is mine.

[bernard towersParticipant @bernardtowers37738]

[Andrew TinsleyParticipant @andrewtinsley63637]

Interesting that GHT mentions tangential tooling in his Workshop Manual. He was pretty disparaging about them, yet lots of members here think they are great.  If I remember correctly (and maybe not!), GHT didn’t like the fiddling with the set up which took time to get it right.

GHT was usually spot on with his comments, perhaps this time he was wrong?

Andrew.

[VicParticipant @vic]

I use mine a lot. I also have a bought one which takes round tool bits as well. Loaded with old broken carbide end mills, suitably sharpened, it can tackle many jobs.
I wonder what GHT means exactly by “set up”?

The best design of Tangential tool holder is the type where you flip it upside down on a flat surface to set the bit height. I didn’t think of this when I made mine so I use a height setting post instead.

[Howard LewisParticipant @howardlewis46836]

At least two designs have been published in MEW to make a Tangential turning tool (Both using 1/8″ toolbits) and a simple grinding jig.

I have made several, (Using, 1/8, 1/4″ and 5/16″ toolbits; and a 1/8″ round bit) in addition to buying the Eccentic Engineering version.

A vast amount of my turning work is done using tangential tooling, and it produces very good finishes.

It will take cuts of 0.0005″ or 0.050″ a side with equal sucess, on a varety of lathes. (mini lathe, 12 x 24, Colchester, Loughborough, Milnes, Raglan, and others)

So much as I admire GHT, here our opinions diverge.

Simple to make, regrind, and effective in use. And quite long wearing. A light grind very soon restores the edge, so it takea a LONG time to wear out the toolbit.

Howard

 

 

[bernard towersParticipant @bernardtowers37738]

surely flipping it upside down doesnt give centre height but puts the tool tip at the same height as the holder? that doesn’t necessarily put it at the correct height for the lathe.

[Paul KempParticipant @paulkemp46892]

I have never (knowingly or as far as I remember) used a tool holder of this type.  Hesitate to call them tangential because are not all cutting tools presented at some sort of tangent to the work by nature of the angles they are ground to?

I guess for multiple people to be singing their praises there must be some benefit but I struggle to understand why there are claims of superior finish through their use?  Surely if you grind a conventionally held HSS tool bit to the same angles then the finish would be the same?

As far as I can see the only real advantage is with a jig it is easier to grind the tool to a repeatable geometry?

Paul.

[Martin KyteParticipant @martinkyte99762]

I would hazard a guess that they may be a little more rigid than the equivalent conventionally ground HSS tool having the same ‘stick out’. The lump on the end of the tangential tool holder is quite substantial.

For smaller lathes it is surprising how much a bit of extra overhang adversely affects finish.

regards Martin

[bernard towers]

On bernard towers Said:

surely flipping it upside down doesnt give centre height but puts the tool tip at the same height as the holder? that doesn’t necessarily put it at the correct height for the lathe.

I use mine in a QCTP, so setting the tip level with the top of the tool gives repeatability after regrinding, as the tool holder only needs to be set to give centre height on the first use.

Rob

[bernard towers]

On bernard towers Said:

surely flipping it upside down doesnt give centre height but puts the tool tip at the same height as the holder? that doesn’t necessarily put it at the correct height for the lathe.

Well it does if it’s made to suit the lathe. As I said, I didn’t think of this when I made mine but I’ve seen others make them.
To be honest though, tangential tools are great for four way tool posts as they have their own height adjustment.

[Martin Kyte]

On Martin Kyte Said:

I would hazard a guess that they may be a little more rigid than the equivalent conventionally ground HSS tool having the same ‘stick out’. The lump on the end of the tangential tool holder is quite substantial.

For smaller lathes it is surprising how much a bit of extra overhang adversely affects finish.

regards Martin

Not sure I subscribe to that generally.  Possibly the shank is bigger than a conventional tool so agree would be more rigid if you had more overhang but only in a rigid tool post and lack of play in cross slide and top slide.  Looking at the linked video there was definitely a lack of ridgidity in the tool holder the video maker demonstrated – mk1 distorted!  Some of the other holders in this thread are a better design but you still need material in front of the tool.  Less overhang I think is doubtful when you consider the gubbins holding the tool bit into the holder.  Normal HSS in a four way tool post only needs to protude by a bit more than the maximum cut you intend to take or to clear a bigger diameter past a shoulder.  Has anyone tried grinding a conventional tool to the same effective geometry and features and done a comparative test?

As I said, never tried one so can’t speak with authority I just done see why it should give a better finish.

Paul.

[Vic]

On Vic Said:

They are easy to make, this is mine.

The tool holder looks very nice! Is it painted? But I don’t think this model is easy to make. At least not by me.

[Paul Kemp]

On Paul Kemp Said:

On Martin Kyte Said:

I would hazard a guess that they may be a little more rigid than the equivalent conventionally ground HSS tool having the same ‘stick out’. The lump on the end of the tangential tool holder is quite substantial.

For smaller lathes it is surprising how much a bit of extra overhang adversely affects finish.

regards Martin

Not sure I subscribe to that generally.  Possibly the shank is bigger than a conventional tool so agree would be more rigid if you had more overhang but only in a rigid tool post and lack of play in cross slide and top slide.  Looking at the linked video there was definitely a lack of ridgidity in the tool holder the video maker demonstrated – mk1 distorted!  Some of the other holders in this thread are a better design but you still need material in front of the tool.  Less overhang I think is doubtful when you consider the gubbins holding the tool bit into the holder.  Normal HSS in a four way tool post only needs to protude by a bit more than the maximum cut you intend to take or to clear a bigger diameter past a shoulder.  Has anyone tried grinding a conventional tool to the same effective geometry and features and done a comparative test?

As I said, never tried one so can’t speak with authority I just done see why it should give a better finish.

Paul.

My point was to consider the two types on the same lathe with the same distance between the tip and the edge of the toolpost. The only difference is then the stiffness of the bits that hang out.
The only other factor would be the ease of sharpening to correct angles and finish which I suspect is a major contributor in tangential tool holders. I don’t have one so I’m just thinking through the issues.

regards Martin

[Andrew Tinsley]

On Andrew Tinsley Said:

Interesting that GHT mentions tangential tooling in his Workshop Manual. He was pretty disparaging about them, yet lots of members here think they are great.  If I remember correctly (and maybe not!), GHT didn’t like the fiddling with the set up which took time to get it right.

GHT was usually spot on with his comments, perhaps this time he was wrong?

Andrew.

What exactly does he say?  My copy of George Thomas’s Workshop Manual has gone AWOL.

I’ve never used one, but loads of people rate them highly.   I think the advantage is they deskill tool-grinding, making it easy to keep an HSS cutter in good order.   Chaps who have the knack of grinding HSS often assume everyone else will find it easy too, which ain’t so!  Cack-handed types like me would definitely benefit from tangential grinding simplicity, though I actually prefer carbide inserts supplemented by painfully bodged conventional HSS grinds.  Though my results aren’t pretty or quick, they work well enough.

The disadvantage of tangential cutters is they only do one type of cut, though this is probably by far the most common.

My guess is someone as experienced and skilled as GHT wouldn’t get much benefit from a tangential holder because he could quickly grind whatever he needed for optimum results in all circumstances.  But unskilled and semi-skilled grinders would save a lot of time and bother by using them – a way of getting good results from HSS with less fuss.

Dave

[duncan webster 1Participant @duncanwebster1]

……

The disadvantage of tangential cutters is they only do one type of cut, though this is probably by far the most common……

Dave

Mine will do parallel turning and facing at one setting. Same as a carbide insert. It will also do screw cutting if you follow the instructions for grinding the tool bit, although I usually just grind a bit of HSS.

[Roderick JenkinsParticipant @roderickjenkins93242]

I can’t find any reference to tangential tooling in the indices of either GHT’s Workshop Techniques or Workshop Manual.  Tubal Cain mentions them in his Simple Workshop Devices:

 

Possibly, long before Eccentric Engineering made their version, GHT was referring to the type described by TC which rests on the bed of the cross slide and, as TC mentions, is very awkward to set up.

Rod

[Paul KempParticipant @paulkemp46892]

Rod,

That fig 74 makes perfect sense, removes tool post, potentially top slide and puts the tooling force close to vertical on the cross slide.  However that is a long way removed from having a tool holder in the tool post holding the tool in the same attitude.  I have used the screw jack dodge to good effect on tools with unavoidably long overhang.  Adding that feature to the tangential tool holders shown by others on here may be a useful compromise in adding rigidity and show a tangible result over and above the advantage of a simple grind.

Paul.

[Sonic Escape]

On Sonic Escape Said:

On Vic Said:

They are easy to make, this is mine.

The tool holder looks very nice! Is it painted? But I don’t think this model is easy to make. At least not by me.

It’s just sandblasted, then given a coat of wax to help prevent rusting.

[Martin of WickParticipant @martinofwick]

Couldnt say whether TTs give a better cut or not as a consequence of design parameters, probably not and likely no difference between a TT and a well ground and set conventional tool for finish.

In my experience, the utility and cutting qualities of TT come form the fact they are dead easy to grind correctly and keep razor sharp (by using a simple jig and a wipe across a sanding disk). They are also easy to set correctly and to height, compared to having to pack into a conventional toolpost (not having the usual 40 or 50 QCTP holders that most people seem to have).

For those of us without a toolcutter and who have to rely on some dubious grinder offering from the local DIY store TTs are  a great benefit, you can always have a sharp tool in seconds with minimum effort.

I have ground (or attempted to grind) function specific tools ‘like wot they show you in the books’, but found it far from trivial.  More often than not, after hours of reducing expensive HSS to a carpet of abrasive dust all over the workshop, I am rewarded with a multi faceted horror, of doubtful cutting quality.  Come the time to re-sharpen said horror, repeating the angles never seems to go well, and using a slip stone is not satisfactory either (before anyone shouts out). And then it all has to be packed up to height again because the dimensions change as you cut back the edges of angled surfaces, etc.

Thing is, you can get away with a less then perfect tool for ‘yer bog basic steels etc, but the truth about the shoddy condition of your cutting edges can suddenly and unpleasantly be revealed when you come to hack away at something a bit tougher, PB or SS for example. This is where a TT can make life easy.

The TT is not a universal panacea, just a very useful go to cutter in the dilettante’s workshop. One of the best returns on time and effort to make I have experienced.

 

[Alan JacksonParticipant @alanjackson47790]

Apart from it being easier for grinding the one top face I fail to see the advantage in the Tangental tool as it is called.

The biggest disadvantage it seems is that it increases the cantilevered overhang distance from  the edge  of the cutting tool to  the support surfaces of the topslide dovetails, which is the first point of support, as it is not supported directly below the tool as is shown in Fig 74.

Alan

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