Router bit too large for insert plate

[stephenharris]

I own a (Katsu) palm router, and in order to cut some groves to take 5.5mm ply, I bought a 7/32" slot cutter and table insert.

Unfortunately I failed to account for the diameter of the bit (~50mm) which is too wide to fit through the plate (42mm).

I think I might be able to insert the bit after the router is mounted (I haven't yet made the "table"). But failing that, could I use the slot cutter to widen the hole in the plate?

Its a TCT bit, so could it cut through 4mm of aluminium? (it's just the shelf the insert plates sit on that is in the way). It would mean I couldn't use the inserts, but that's OK- the plate was only £10.

Or should I just look for another plate with a wider diameter?

 

[Sideways]

50mm dia cutter in a katsu edge trimmer. That's aspirational

You're using the wrong tool for the job. Too small, too underpowered, wrong ergonomics and never intended for a cutter like that.
Get a proper 2 handled plunge router.

 

[sometimewoodworker]

I own a (Katsu) palm router, and in order to cut some groves to take 5.5mm ply, I bought a 7/32" slot cutter and table insert.

Unfortunately I failed to account for the diameter of the bit (~50mm) which is too wide to fit through the plate (42mm).

I think I might be able to insert the bit after the router is mounted (I haven't yet made the "table"). But failing that, could I use the slot cutter to widen the hole in the plate?

Its a TCT bit, so could it cut through 4mm of aluminium? (it's just the shelf the insert plates sit on that is in the way). It would mean I couldn't use the inserts, but that's OK- the plate was only £10.

Or should I just look for another plate with a wider diameter?

There is no problem with using a router to cut aluminium, you will not damage the cutter or the router, if careful.

As to the advisability of doing it and using such a bit on such a router, that is completely different, @Sideways is probably right.

personally I have steel router plates with a number of aluminium inserts so I can cut large/ custom holes if I need to.

 

[stephenharris]

Thank you for the advice! Regarding the router not being powerful enough, is the the issue with the router bit/type of cut or is it the depth of cut?

I only need a groove of about 5mm deep, which I was going to do on muiltiple passes. That the bit can cut a depth up to ~15mm was simply because I couldn't find any other bit with the desired kerf.

I'd like to avoid shelling out for a second router if I can... so would multiple passes on a smaller (kerf and depth) bit be possible or am I just trying to hammer in a screw at this point?

 

[paulrbarnard]

Thank you for the advice! Regarding the router not being powerful enough, is the the issue with the router bit/type of cut or is it the depth of cut?

I only need a groove of about 5mm deep, which I was going to do on muiltiple passes. That the bit can cut a depth up to ~15mm was simply because I couldn't find any other bit with the desired kerf.

I'd like to avoid shelling out for a second router if I can... so would multiple passes on a smaller (kerf and depth) bit be possible or am I just trying to hammer in a screw at this point?

Because the cutting point is so far out from the spindle it will put a massive load on the router motor. Add to that the depth of cut and you could easily overload the router.
The main danger though is safety. The torque/inertia of the large cutter with a small light router means it could easily grab and damage the work or you.

 

[worn thumbs]

I agree with the posters who say its the wrong machine for the job.Two things stand in the way,first the simple physics of the cutting edge being so far from the axis of the machine and second,the small amount of power the router has.You would have a greater chance of success if you could locate a 7/32 diameter cutter and machine the groove in several passes.

 

[Spectric]

All of the issues are simply down to the wrong tool for the job in hand, a groove 5mm deep and 5mm wide may seem trivial but there is some volume of wood to be removed and the work needed to be done by the router will be very dependant on the wood, if it is a hardwood then even a big router in a table will be working hard. The easier way to do this job if the slots for the panel are central is to use a smaller cutter and take two passes to get the 5.5mm width running the router fence using both faces of the work.

 

[dizjasta]

 

[ChaiLatte]

From my reading of his post, his cutter is similar to this:

https://www.precisionbits.com/7-32-slotting-cutter-router-bit-1-4-shank-yonico-12106q.html
You have to ask yourself that if death and destruction will occur when he uses the bit in his machine, why is it on sale in multiple places? Alternatively, given that it is on sale in 1/4" shank, what is necessary to use it in a satisfactory manner?

If the cutter has to be secured in the machine before the insert is located in its pocket, the insert does not necessarily need to go in over the cutter from the top. Buy an insert with a 7mm diameter hole in it, use a hacksaw to make that hole into a slot (that faces the non-fence side of the cutter) and poke it in from the side/front.

 

[Sideways]

A trim router is all about compact size and single handed, body grip use. They have small and relatively low power motors as a result of the size constraint. That is a good thing as you can't control a a tool with a powerful motor as well with one hand as you can with two.
The trim router has a small baseplate as standard which again is OK for their designed purpose of edging, rounding, small mouldings, rebates and grooves, but doesn't provide stability to control a large cutter freehand.

Screw a trim router to a plate and you can overcome the stability issues but not the lack of motor power and torque. Your 50mm cutter has almost 8x the diameter of the 1/4" shank that has to twist it against the resistance of the wood at the cutting tip. That's a lot of leverage. Rather like trying to drive a car up a steep hill in top gear you are not being kind to the motor. To make things worse as cutter diameter gets larger, you should reduce the speed of the router to keep the speed of the cutting tip through the material in the best range. Slowing down the motor (probably below half) reduces both power and torque so you have even less to work with ....
To make this work you would be advised to take very light cuts and feed slowly.

So, if you understand that you are using the wrong tool for the job as all of us sometimes do, go slow and easy when you try this out.
Your cutter is a slot cutter that will be coming into the stock from the side to make a relatively narrow groove for you to insert a panel into.
This doesn't need you to alter the router plunge depth once you have it correctly set, yes ?
So plunge your router as far as it will go with no cutter in place. Lock the plunge. Insert the cutter from below the baseplate then tighten the collet. Adjust the plunge depth with the power off.
Once set, make your cuts lightly (adjusting whatever fence each time to allow the cut to deepen one or two mm each pass) and whatever you do, don't forget and unlock the plunge until you have taken the cutter out again. No need hopefully to cut the base of your router or whatever plate you bought for it.

For info, a job like this is a key part of the process for making loose tenon shaker style cabinet doors on the workbench.
Peter Millard has a nice video where he uses a router under a bench. See 1minute 30s in.


But with a traditional elu mof96 style router, that task is easily done using the router handheld. You'll find that type of router is more versatile than a trimmer and will do almost everything the trimmer can and much more, you just can't use it single handed.

 

[Spectric]

From my reading of his post, his cutter is similar to this:

If it was a straight slot cutter then it would fit through his router base,

I bought a 7/32" slot cutter and table insert.

Unfortunately I failed to account for the diameter of the bit (~50mm) which is too wide to fit through the plate (42mm).

I would suspect it is actually like this , https://www.amazon.co.uk/Trend-C145X1-4TC-Slotting-6-3mm/dp/B0001P11JS/ref=sr_1_5?keywords=slot+cutter+router+bit&qid=1701604203&sr=8-5&th=1

 

[niall Y]

If the OP purchases a 1/4" arbor with interchangeable cutters that can be bolted on after it has been fixed in the router collet , then it will be a lot more convenient to use. You have of course , be mindful you don't put the cutter on upside down.

 

[paulrbarnard]

If it was a straight slot cutter then it would fit through his router base,

I would suspect it is actually like this , https://www.amazon.co.uk/Trend-C145X1-4TC-Slotting-6-3mm/dp/B0001P11JS/ref=sr_1_5?keywords=slot+cutter+router+bit&qid=1701604203&sr=8-5&th=1

View attachment 171014

Yes that’s what I understood. The OP would be better off with the type posted by @dizjasta with a trim router.

 

[stephenharris]

@dizjasta previously I have used that to make a drawer using the 1/4 1/4 1/4 method. I used an undersized straight bit (I didnt know the exact dimensions of the ply, I just knew it would be thinner than advertised...) and routing jig to cut the dados and rabbets. It worked, but I figured a slot cutter on a table would be easier and less error prone, particularly as I wanted to try shaker-style doors.

The replies here though have made me realise I can still get the repeatability and stability of a table, but still use an straight bit, though I'll get a 7/32 one to make my life easier.

And if I end making many more of these type of cuts I'll look into getting a beefier router.

Thanks all!

 

[eribaMotters]

I own a (Katsu) palm router, and in order to cut some groves to take 5.5mm ply, I bought a 7/32" slot cutter and table insert.

Unfortunately I failed to account for the diameter of the bit (~50mm) which is too wide to fit through the plate (42mm).

I think I might be able to insert the bit after the router is mounted (I haven't yet made the "table"). But failing that, could I use the slot cutter to widen the hole in the plate?

Its a TCT bit, so could it cut through 4mm of aluminium? (it's just the shelf the insert plates sit on that is in the way). It would mean I couldn't use the inserts, but that's OK- the plate was only £10.

Or should I just look for another plate with a wider diameter?

If the bit will be to large for the insert plate then it will be to large for the router. Do not use it, it's not worth the risk.

Colin

 

[Mickjay]

Have you considered getting the plunge base for router? They are available on Amazon and eBay. It has a larger aperture than the fixed base so may take your slotting bit without any modification. Obviously the power issue still exists but you have more control over the router.

 

[stephenharris]

@Mickjay I do, and it does, but it's the table plate that the bit won't fit through.

And as you mention, there is still the issue with the router not being powerful enough.

 

[Sachakins]

Do you have a table saw?
If so a slot cutting blade would be easier.
CMT do a 6 mm slotting blade, something like this
CMT Orange Tools 240.060.06 M - Circular Saw Blade for Groove Cutter 150 x 6 x 30 Teeth 12 https://amzn.eu/d/9zsaMf5

 

[sometimewoodworker]

@stephenharris When all you have is a hammer everything becomes a nail.

You need accurate, deep slots.
You have a tool that will do the job that has drawbacks. The drawbacks are that 1) a slot cutter for that depth should probably be on a ½” shank or 8mm shank bit unless the amount of bit above the arbor is at the minimum. This is due to the rotational speed required (not very fast) drawback 2) the router you have will need several passes and even then it may not do the job.

Possible fixes, 1)
as suggested use a different bit, Drawback, in my experience a straight bit is more likely to not cut as accurately as a slot bit.
2) and the one I would use, reduce the work that the bit needs to do by using a table saw with a thin kerf blade to run an undersized slot before using the router table.
3) probably many I haven’t thought of.

 

[sometimewoodworker]

but it's the table plate that the bit won't fit through.

I have run bits too large to plunge through the table by fitting them into the collet from above the table.
Easy? No. Possible? Yes. Advisable? Probably not.