Mortise cutting basics ? little help.

[dmede]

This is not directly boat related, its just wood related but I couldn't imagine posting it in the bilge so here I am.

I'm going to be putting together a very basic bed frame with mortise and tenon joints next week and would like some tips on cutting the mortises. Whats the basic technique for excivating the mortise?

Dave

[P.I. Stazzer-Newt]

Bob Smalser did one. Mortices (http://www.woodenboat-ubb.com/ubb/ultimatebb.php?ubb=get_topic;f=1;t=008649)

The pictures have gone missing but its worth reading.

The article on Chisels for Beginners (http://www.woodcentral.com/cgi-bin/readarticle.pl?dir=smalser&file=articles_472.shtml) is worth reading.

[ 12-20-2005, 06:08 PM: Message edited by: P.I. Stazzer-Newt ]

[marwesmed]

Dave, I think that the going thing today is using a Plunge Cut Router and a fixture to guide you. The tenons would then have the corners rounded to fit the mortises.

[Hal Forsen]

It depends on what tools you have on hand; The old timers made do with just a proper sized Mortise chisel and mallet.
http://www.oldtools.com/FW10840.jpg
Some folks use a router but for just a few joints I find the set up usually takes longer then the job itself.
If you don't have mortise chisels and aren't going to use a router it's typical to drill overlapping holes (more easily done with a Forstner type bit) and then pare down the sides and ends with a paring chisel.
http://pages.friendlycity.net/~jrucker/Bench/BaseHoles.jpg
If it is a blind mortise a swan neck chisel is handy for cleaning out the bottom of the mortise.
http://www.traditionalwoodworker.com/images/225-6038%20lg.jpg
My 2 cents.
HF

[dmede]

Good link P.I., too bad the pics are gone, I'm very visual so thats realy what I need. but the descriptions should help a lot.

I should have mentioned that I intend to do this with a 1/2" mortise chisel and mallet. Trying to teach myself something new and I prefer the low tech approach for starters. It is a blind mortise, where the bed rails plug into the legs. The front and back rails will have full size tenons (1.5" deep) while the side rails only have a very shallow tenon (1/2" deep).

The wood is Alder.

[Bob Smalser]

Drill and pare...or chop. Your choice. Chopping is much faster, but only works well thru around an inch-wide mortise, larger ones are generally drilled first.

http://www.woodcentral.com/cg i-bin/readarticle.pl?dir=smalser&file=articles_608.shtml (http://www.woodcentral.com/cgi-bin/readarticle.pl?dir=smalser&file=articles_608.shtml)

http://www.woodcentral.com/cg i-bin/readarticle.pl?dir=smalser&file=articles_441.shtml (http://www.woodcentral.com/cgi-bin/readarticle.pl?dir=smalser&file=articles_441.shtml)

http://www.woodcentral.com/articles/images/608e.jpg

The gooseneck chisels are primarily for exceptionally long lockset mortises. You can scrape the bottom of a short mortise clean faster using a common mortise chisel, indexing the bevel against the mortise end as a fulcrum to scrape the bottom. With long millwright chisels, I can get a whole half-inch of additional depth this way, eliminating an entire chopping sequence.

http://pic3.picturetrail.com/VOL12/1104763/5536778/102807533.jpg

I also use a plunge router and slip tenons (easier than conventional tenons and just as strong) made of stock rounded with a roundover bit on the router. Depends on how many I have to do.

[ 12-20-2005, 06:37 PM: Message edited by: Bob Smalser ]

[Ron Williamson]

When hand chopping mortises,it's nice to work on the most solid part of your bench,like over a leg,cuz things don't bounce around as much.
R

[dmede]

I'll be chopping, Ive been looking for a 1/2" millwright chisel but to no avail. I will most likely have a new or used "registered" mortise chisel next week when I return home and begin this project.

My marking guage is a shop made one (by me, and not that great) and does not have "double tines" for outlining the mortise. Can I get away with marking my tenons without it or should I pick one up?

[ 12-21-2005, 01:44 PM: Message edited by: dmede ]

[Bob Smalser]

Originally posted by dmede:
I'll be chopping, Ive been looking for a 1/2" millwright chisel but to no avail.

My marking guage...does not have "double tines" for outlining the mortise. Can I get away with marking my tenons without it or should I pick one up?How thick is your rail stock that'll receive the half-inch tenon? No thicker than one inch, eh?

I've got an half-inch W. Butcher bolstered English pigsticker laying around you can have if you want it.

The tine marks help to prevent the sides of the chopped mortise from splitting out. Strike the outline with a paring chisel if you don't have one...but if you plan to chop many mortises in your life, I'd get invest in one promptly.

[dmede]

I would love to have a hand-me-down chisel. I don’t like buying new tools for tasks I haven’t learned yet. I’ll contact you off the board.

The rails are 1" nominal so really about 13/16". Not ideal but it was my only choice without committing to some expensive milling (I really need a band saw).

The posts (or legs) that I'll be cutting the mortises into are just two pieces of my rail stock glued up into legs, finished they will be 2" x 1.5". The short 1/2" tenon will go into the 2" face while the longer 1.5" tenons will go into the 1.5" face on the leg. Does that make sense?

[George Roberts]

dmede ---

I just made some beds. I found it easiest: to bandsaw the tenons to size +.01" then to drill a series of holes for the width of the tenons.

A bit of work on the mortices with a bench chisel and a touch of sandpaper on the tenons and the work is done.

It is easy enough to get the bottom of the mortice flat enough with a bench chisel.

I hope you are using bed bolts so you can take the frame apart. On the other hand 13/16" is a bit thin for bedbolt nuts.

[ 12-21-2005, 01:21 PM: Message edited by: George Roberts ]