Thread: Router Cutters for Mortising

Graeme. You need to use solid carbide spiral upcut cutters for morticing. They are available from McJing and Carbatec, if they have them in stock. The 3/8" cutters have a cutting length of 32 mm.

Rocker

Hi Graeme,



Woodrat have some HSS bits that may be suitable - see <TABLE cellSpacing=2 cellPadding=0 width="95%" border=0><TBODY><TR><TD style="TEXT-ALIGN: left" vAlign=top width=350 colSpan=2>[WRHS50H] STRAIGHT BIT H-S-50-H . Nicely made, but a bit pricey at AU$65<TABLE><TBODY></TBODY></TABLE></TD></TR><TR><TD style="TEXT-ALIGN: left" vAlign=top width=350 colSpan=2>

Excellent for general morticing and making tenons as well as dovetail pins. D:12.7mm (1/2") H: 50mm S: 1/2"



They're available from Carba-Tec WA, and CMT carbide bits from Carba-Tec generally. Timbecon, also in WA have the Torquate range, see:
1/2inch Shank Straight Router Bits - SB-6-MH
Straight bits have two tungsten carbide cutters Straight bits are available in both imperial and metric sizes for both 1/4in and 1/2in shanked bits. The most common straight bits are available in standard cutting lengths as well as extra long (50mm - X Series) cutting length bits. Specifications for bit is as follows: D = Diamteter, L = Length of cutting edge


Cheers!
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Steve,

Straight bits are not really suitable for morticing, although they can be used at a pinch. Straight bits are not usually designed for plunging, as spiral bits are. I would strongly recommend sticking with the solid carbide spiral bits. HSS would do if you only intend to give them light use.

Rocker

Graeme,
For mortising I generally use either of the following. A straight HSS woodrat cutter, they are available from carbatec in Perth and come 8mm, 10mm or 12.7. These straight cutters work brilliantly for mortising and not only for light work. They have a cutting length of 50mm with a approx overall length of 70-75mm. The other benfit is that you can sharpen them yourself, mim down time. The other cutter I use a lot is a cmt upcut spiral cutter 12.7mm dia with a cutting length of 50mm. Cmt will cost you approx $100 and the woodrat approx 65 last time I bought one. Both cutters work very well when cutting deep mortices. I also use the same cutters to cut the tenons with in my jig which does both the mortice and tenon.

Rocker, regarding using spiral bits for morticing....

So far I've been using carbice STRAIGHT bits with plunge cutter heads. I go down about 5-8 mm at a time then forward & back in my morticing jig. (I have a Triton router with hand held rotating plunge mechanism. Allows for a very controlled plunging technique) So after about 5 to 8 passes, my mortice is done. Very clean and accurate.

I've been wondering whether I should change to spiral bits (having read they're commonly used for routing mortices), but I'm not sure how the technique works. Do you spiral down to the full depth of the mortice in each plunge, repeating the full plunge along the length of the mortice? (And does that leave any clean-up work for chiseling / or a final lateral swipe with the spiral bit) - Or do you plunge down 5-10 mm then clean out the full mortice at that depth? Not sure if I've said that clearly. But I think you'll understand what I'm trying to ask.

Thanks,

Richard

Richard
the spiral bits are a joy to use for morticing compared to a straight cutter.

My method for cutting deep mortices is to plunge to full depth at the start of the mortice, raise the bit and move along about half the cutter diameted and plunge again to full depth.
I continue this until I get to the end of the mortice then plunge to full depth and make a complete pass of the mortice.

This puts minimal pressure on the bit and gives a very clean cut.

If I was only cutting a shallow mortice, say 10mm, I would probably plunge to 10mm and cut the mortice in one pass.

Richard,

The technique that I use with solid carbide spiral upcut bits on my morticing jig, see http://www.woodworkforums.ubeaut.com...ead.php?t=5633 , is as follows: I stand with the fence between me and the router, and position the router at the right hand end of the mortice. Then, keeping the router stationary, I plunge the bit to the full depth of the mortice in two or three plunges; I then adjust the depth control to take a pass of about 6 mm, and plunge the bit to this depth in the hole just routed and then make a pass to the left hand end of the mortice. I then return the router to the right-hand end, adjust the depth to take another 6 mm, and repeat the process until the full depth of the mortice has been routed. Although the spiral cutter resembles a drill bit, it will cut sideways in shallow passes, just as a straight bit will.

Most straight bits are not designed to be used for plunging, and, if you attempt to plunge with them, will just cause burning in the centre of the bit where there is no cutting edge. Some straight bits are designed for plunging, but, even so, they are far less effective in removing the cuttings from the mortice than a spiral bit is. It is feasible, but much less effective, to use a non-plunging straight bit to rout mortices by using a technique of making sloping passes, rather than plunging. But I feel it is best to get the right bit for the job - a spiral upcut one. Using one of these, I can normally rout a mortice in less than a minute on my jig.

Rocker

I use proper mortise & tenon bits as per this link:
http://www.northwoodtools.com.au/category208_1.htm

Thay have a 10% off sale at moment too.

Might be worth a look.

Ingrid H

P.S. Yes I have a vested interest, I work for Northwood part time as book keeper, but I also use the product when I am routing.

Thanks to all those who replied and for the ongoing discussion.

I will be making enquiries at the places suggested.

Thanks once again

Originally Posted by Rocker

Steve,

Straight bits are not really suitable for morticing, although they can be used at a pinch. Straight bits are not usually designed for plunging, as spiral bits are. I would strongly recommend sticking with the solid carbide spiral bits. HSS would do if you only intend to give them light use.

Rocker

Hi Rocker,

Thanks for that bit of corrective advice. I don't rout mortices very often, but have been wondering why they're not all that effective - duh!!

Order clearly due for some up-cut spiral bits What are the shares in CT doing at the mo' ? If I go there (new store in Springvale) much more, they'll probably put in a camp bed for me. Hmm!, if I were to take some wood with me...Nah, they'd just throw me out

The HSS bits I mostly use on the WoodRat for tenoning, edge trimming and so on, and they're beautifully machined, easy to sharpen and, well, just look like precision tools...

Cheers!

Originally Posted by render2017

I use proper mortise & tenon bits as per this link:
http://www.northwoodtools.com.au/category208_1.htm

Thay have a 10% off sale at moment too.

Might be worth a look.

Ingrid H

P.S. Yes I have a vested interest, I work for Northwood part time as book keeper, but I also use the product when I am routing.

G'day Render,

Just gone there and done that! Thanks!

Cheers!

Scally / Rocker,

I get the picture now. I've been using straight bits but with the plunge cutter edge on the bottom (but even then it doesn't plunge well). The annual Timber & Woodworking Show is on in Perth August 12-14. I'm making a trip up and will be buying some spiral upcut bits.

Thanks

Richard

Great that you ordered some. If they follow normal practice, they will phone you to confirm order (did you give them phone number?) and also confirm shipping costs.

This is a new range for them, but I was lucky, the manager had me play with the samples, I rate them at least the equal of CMT, and in most cases same or lower price.
They use a C4 micrograin so are super sharp, and stay that way longer, have a full warranty too. The range is quite extensive, and if you check the part number, they closely correspond to the CMT numbering for some reason I was not able to confirm why. I know they come from Italy !

Hope they do the job for you.

I only work there one day per fortnight to balance the books !

Regards Ingrid