why are reversible routers and bits not a thing?

[Yojevol]

Can you explain more, what is the difference between moving your workpiece in the opposite direction compared to the cutter spinning in the other direction ? Is this yet another plus for the spindle !

The difference is the orientation of the grain angle compared with direction of feed. Turning the cutter over and rotating in the opposite direction will only work if you have a symmetrical cutter profile, eg straight, or circular as in the above video.
Brian

 

[niall Y]

Probably done using a French head, lovely hand eaters / missile launches and one of the reasons the spindle has its reputation.

Interesting video, I have come across these cutter heads, but the shaft would have to be far slimmer to achieve the small radiuses I have seen. Perhaps some of the examples I have noted did use machine routers, examples of which seem to go back to around 1915'ish.

 

[deema]

It’s also amazing what can be done by hand, carving out the profile in tight corners.

 

[johnnyb]

I'm thinking the chamfer work on Sussex wagons looks routered work but was done by hand.

 

[Derek Cohen (Perth Oz)]

Have you tried a compression router bit?

Regards from Perth

Derek

 

[johnnyb]

hi Derek







I'd just firstly like to thank you for a blog post where you advocate sharpening your bandsaw blades using a dremel....that is solid gold and saved me loads!. ( I've got the same saw)any way i did use a compresion trimmer and it works beautifully. what is your thoughts on reverse routers and bits? saying its to specialist a role is a non starter because there are loads of even more specialist stuff around.

 

[Hornbeam]

You can bolt the TCT cutter in upside down and you have a reversed cutter

Absolutely No No No. These cutters are designed so the leading edge of the cutter operates as a chip limiter. The other factor is that I dont know of any routers that operate in reverse. If you tried this on a spindle moulder with a router cutter as you said but the spindle in reverse I thinnk the results could be disasterous. Also the cutters are designed so the forces act onto the cutter body. Setting it up in reverse means all the load would be taken by the set screws

 

[johnnyb]

tbf he does say explicitly don't do this..

 

[deema]

Absolutely No No No. These cutters are designed so the leading edge of the cutter operates as a chip limiter. The other factor is that I dont know of any routers that operate in reverse. If you tried this on a spindle moulder with a router cutter as you said but the spindle in reverse I thinnk the results could be disasterous. Also the cutters are designed so the forces act onto the cutter body. Setting it up in reverse means all the load would be taken by the set screws

Hmmm… the ‘Don’t Do This’ I thought was clear enough and it was an intellectual exercise. However, I actually disagree with your analysis. The body of the router bit acts as the limiter, ie the maximum projection of the blade which is requirement on all routers as well as compliant Spindle moulder setup it has nothing to do with which way around you pop the blades in.
The actual ‘vulnerability edge‘ is the sharp bit, which is the thinnest and sees the greatest force, not the screws, Im almost certain without doing an FEA that the forces on the screws won’t cause catastrophic failure. The manufacturer will have had to do a risk assessment, and putting the blades in upside down will be one of them and using the router. They haven’t poke yoked the cutters so you can’t do it.
Just for reference, I haven’t at any stage suggested using a router bit in this configuration in a spindle moulder, I simply highlighted on a universal motor, the type which is mostly used in Routers (and the subject of the initial post) would need the field windings reversed to get it to rotate backwards.

 

[Inspector]

Since left and right hand milling machine cutters are available one could have a router rewired to turn in the opposite direction, already mentioned (noting there could be an issue with the collet nut coming loose) and use both kind of bits. They are usually simple shapes but custom grinds could be made. It comes down to how often is it needed and is it worth tooling up for it. For a hobbyist like me, nope. A shop doing this kind of work regularly, possibly yes. Note in the machining world there are virtually no bearing guided bits.

https://www.ukocarbide.com/blog/whats-the-difference-between-left-and-right-end-mills/
There are LH bits for CNC routers, not to be confused with hand held routers.
https://www.mscdirect.com/industrialtools/left-hand-router-bits.html
Pete

 

[johnnyb]

�

really my point was to say this would be useful and then garner others opinions. it's definitely not something that could be cobbled together having some safety issues but manufacturers are sometimes trying to develop ideas and this seemed like a good un to me. little known fact but the mafell router is used in a timber framing system for cutting little rounded tenon and mortices.
this is really a development of already existing stuff bit like virutex stuff.

 

[Doug71]

Well I think it's a great idea, imagine doing curved template work and having 2 routers set up, one to run clockwise and one anti-clockwise and just swapping between them as the grain direction changed, it would be so much quicker

 

[SkinnyB]

I had some parts which I had to put a chamfer on both sides. One side going with the grain cut beautifully and other side chipped out horrendously. I came across this bit from CMT that's cuts both top and bottom chamfers at the same. This means you don't need to flip the part. Can now cut all the chamfers without any tear out in half the time.

https://www.cmtorangetools.com/eu-en/industrial-router-bits/adjustable-double-roundover-router-bits

 

[Phil Pascoe]

Why are reversible routers and bits not a thing? Economics.

 

[Spectric]

Ideally you want the cutter to turn into the stuff rather than turning out. If it turns out you’re going to end up with spelch. Reversing the direction of feed will make no difference to this. To make this you would spindle one side to the centre, reverse the cutter and spindle direction and then rebate the other side.

That makes some sense and another bonus for the spindle. That french head must be in the same category as dado cutters and I can see why he said they were outlawed, balance issues and if the cutter came loose it would be thrown out with some force. Direction was something that for some reason gave me problems, I had a total mental block but now I just think that the workpiece has to push against the cut otherwise it is a climb cut and you risk losing control unless you are using a woodrat.

 

[Derek Cohen (Perth Oz)]

hi Derek







I'd just firstly like to thank you for a blog post where you advocate sharpening your bandsaw blades using a dremel....that is solid gold and saved me loads!. ( I've got the same saw)any way i did use a compresion trimmer and it works beautifully. what is your thoughts on reverse routers and bits? saying its to specialist a role is a non starter because there are loads of even more specialist stuff around.

Johnny, thanks for your kind words.

With regards reversing routers, it is not something I have considered, mainly because the router bits would need to be reversible as well. I do not know of any. The only bit that came to mind is the compression bit, as these can deal with reversing grain.

Regards from Perth

Derek

 

[recipio]

I used to fit side rail hinges on boxes by routing the left hand of the lid and the right hand of the box with climb cuts. I often thought a reversible router would solve that - it's a white knuckle experience. Thankfully Rockler in the US market a jig for side rail hinges now although most people on the Tube still show the back routing technique.

 

[niall Y]

Surely, any router cutter comprising an arbor, with cutters stacked on it , can be made to cut in reverse, by simply turning the cutters upside-down?

 

[Inspector]

Surely, any router cutter comprising an arbor, with cutters stacked on it , can be made to cut in reverse, by simply turning the cutters upside-down?

Yup to a point. That flips the profile so if you flip the part to match you are cutting in the same direction as before the flip and gain nothing.

Pete

 

[johnnyb]

mention of French heads brings to mind this video saying why they were useful( in certain types of work) and the dangers inherent. basically they allowed the profile to be shaped exactly as the slot is central(no rake) leading to a scraping cut. they could also be fitted with rub rings not unlike bearings on a router cutter. the dangers were simplicity of attachment re cutter and spindle. also kickback due to no limitation and a scraping cut. cutters weren't usually hardened as another problem was overstretching of profiles leading to breaks.