Timber framing - cutting mortises

[AJB Temple]

I am making a couple of timber frames shortly, and have about 120 mortises to cut in green oak beams of either 175 x 175 or 150 x 150 cross section. Some of these are sunken mortises. The tenons are no problem.

These mortises need to be done on the assembly site where the buildings will be erected - which is about 60m away from my workshop. Some of the timbers are 6 metres long and I can't even get them in the workshop. Anyway, I don't have a big mortising machine.

I know the ideal answer is a chain mortiser. However, a Mafell one is £2,500 and a Makita is around £1200 (with a flimsy plastic chain guard), which is quite a big chunk of change for a machine I doubt I will ever use again.

So I am just wondering if there is something I am not aware of that will be reliably quicker than a big bit in a drill, followed by chisel and hammer work. I know some people are confident doing this kind of thing using a chainsaw, and I do have chainsaws, but I am not confident doing plunge cuts with them.

It being green oak I don't need to be incredibly accurate, but I am doing this on my own and I do need to get the frame built without too much messing about! Any ideas?

 

[oakfield]

I would be tempted to look for a second hand chain mortiser and sell it on again when finished - I doubt you would loose any money on it.

 

[Wuffles]

I agree with Oakfield, but how deep are the mortices you're cutting? I managed a much smaller job with a router, a jig and a bit extender, rightly or wrongly.

Edit: I didn't see the dimensions before, divvy.


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[RossJarvis]

I put some mortices in some similar size beams recently. I hired a Makaita Chain Morticer. Very reasonable price including delivery and pick up by courier. Much quicker than drilling and chiselling which is what I did for the first few mortices.

 

[AJB Temple]

Thanks guys. I had already looked at the local hire shops and failed to locate a chain morticer for hire. Will obviously look for used, but I don't think these are a common tool.

 

[Markvk]

I think these people will hire to you and send/collect by courier:

http://www.hsstoolshop.co.uk/chain-mort ... 6128-p.asp

worth giving them a call.

Mark

 

[AJB Temple]

Thank you Mark. I will call them later. I am not in a rush as the first load of oak will not be here for about 4 or 5 weeks. I am wondering if I should just bite the bullet and buy a Makita and then sell it next year when I have finished the three structures I will use it for. It just seems a crazy outlay to do one task, but I know it will save me a huge amount of time.

 

[Fitzroy]

Seen a few you tube vids of old timers framing oak. Bit and brace followed by chisel, looks to take 15-20mins per mortise. 120 mortises at 1200 quid is £10 a mortise. So your time would have be worth £40 an hour for a 15m mortise or £20 per hour if they take you 30mins each due to lack of experience. I'd say the outlay is almost justifiable for this single job, and if you sell it on for 50% you would be on a winner. More importantly you get to play with a chain mortiser!

 

[bugbear]

Thanks guys. I had already looked at the local hire shops and failed to locate a chain morticer for hire. Will obviously look for used, but I don't think these are a common tool.

That may mean that buying new and selling after use might be practical, if your only alternative is (expensive) hiring.

Worth checking the numbers.

EDIT; alternatively check North America for s/h; for such an expensive item, the shipping is pro rata cheaper, and there are more timber framers out there.

BugBear

 

[AJB Temple]

Yes, the only cost to me of buying one is the depreciation on sale. This may well work out cheaper than hire and gives me a lot of flexibility, but it does have to pass the wife test as she inexplicably thinks I buy too many tools. As she is in charge of household finances, sleight of hand is not easy.

Hadn't thought of importing from the US so will look into that. Will also try Germany as I see Festool have an offering as well. I seem to remember Zedd telling me that a while ago.

I am very adept at cutting normal mortices by hand, but these are a different ball game. Repetitive work like this easily gives me tennis elbow as well so I am wary of overdoing this kind of task that will require a good deal of hammering, even though I slightly think that using a chain mortiser is cheating. The sunken mortise surrounds are easily enough dealt with by router, so its only the slots I am bothered about. I will need to get a bigger circular saw to speed up the tenon work, but they are not expensive.

 

[Wuffles]

The Festool one looks pretty good actually, you've got contacts in Germany, go for it. You'll probably make money on it when you come to sell it on

 

[AJB Temple]

Yes, I might well get my father -in law on the case. He is over here in a few weeks so he has got time to hunt around for a deal. He got my Mafell track saw at a silly price from some dealer that was selling up. I didn't think about the mortiser at the time but the Mafell ones are crazy expensive in any case. The only snag with the Festool is that it has a maximum depth of cut of 150mm. However that should be enough as most of my main posts are 175mm and I won't be needing through cuts. I think I will hire the Makita one for a day anyway and see of the clamp and plunge system is better than the Festool method.

I had pondered a sword saw for the tenons, but these are really just a glorified chain saw (limited to 200mm cut) and as I already have a couple of those I think I can cover the tenons and general dimensioning with a big circular saw and a chain saw. The sword saw has a riving knife, but that doesn't appear to be useful for tenons as no cut will exceed 175mm.

 

[AJB Temple]

Well, its a funny world. About 30 seconds after posting the above I got an email notification from eBay of a chain mortiser for sale near me that had just gone up. Makita 7101 110 volt model. So I bought that as it was pretty cheap. Then shortly afterwards I got a PM for a helpful member here pointing me towards a Ryobi one. I have been looking onBay and gumtree for weeks and seen nothing useful, then two come along at once.

 

[Bm101]

I know it's not very helpful but don't you have to be a bit careful with the chains on second hands? I seem to remember reading on here someone warning about the cost of them if hiring or buying second hand. Not being negative! Hopefully it's not an issue in the first place but it might be worth checking out or maybe someone can shed some light on it? Looking forward to WIP on this if you're going to do one. AJB.
If I had my time again I think (through rose tinted glasses) I'd have liked to do this for a living. Or Thatching. Or maybe An Oil Baron with a private yacht big enough to have its own submarine. One of the three.

 

[Zeddedhed]

You could also try out an SDS wood chisel. Mikita and bosch both make them. Funnily enough I'm about to order one so I'll let you know how accurate it is once fitted and bouncing around on the end of a cordless SDS drill.

Also, you can cut mortices with a normal chainsaw - just very carefully. Plunge cutting with the tip is something that most people are terrified of but it's a standard technique amongst chainsaw carvers and also tree surgeons/fellers (at least that's what my lumberjack mate tells me)

I have tried it with my little Stihl MS 171 and it's not as scary as you'd think but I wouldn't advise it if you're not 110% comfortable with a chainsaw.