Best way to machine off one side of a large wood beam, in situ?

[Valhalla]

Good idea, but I forgot to say the beam doesn't have parallel sides...

That doesn't matter - as long as they are parallel and they are wider than the beam. Rember - all you are doing is creating a framework on which your router sits which is independent of the beam.

Shame you live too far away otherwise I'd have come and given you a hand - I'm in Cambridgeshire - soon to be Herefordshire

 

[rich1911]

That doesn't matter - as long as they are parallel and they are wider than the beam. Rember - all you are doing is creating a framework on which your router sits which is independent of the beam.

Shame you live too far away otherwise I'd have come and given you a hand - I'm in Cambridgeshire - soon to be Herefordshire

Thanks for the offer anyway!

Basically your version is similar to what I have, but rotated 90 degrees.

The optimal solution would actually be a CNC router bolted to the side of the house! I could carve some designs into the beams afterwards!

If I added a couple of leadscrews (threaded rod) it would make taking each cut a bit quicker.

 

[Stevekane]

Grinder and paint makes me the welder I aint....

The welds are holding fine, this is prototype to prove the concept. It's going in the scrap bin as soon as its done its job.

Now back to the woodworking!

Quite right and if you did want to try the sds wood chisel, I had no idea they existed, you could chop off the sds end of an old drill and weld it to a bootsale chisel, I saw someone do this with a cheap Scutch chisel they wanted to use in an sds drill and it worked just fine.
Steve.

 

[Jameshow]

No one mentioned the angle grinder chainsaw yet?!!!

 

[rich1911]

Quite right and if you did want to try the sds wood chisel, I had no idea they existed, you could chop off the sds end of an old drill and weld it to a bootsale chisel, I saw someone do this with a cheap Scutch chisel they wanted to use in an sds drill and it worked just fine.
Steve.

Hmmm I do have an SDS drill so I may give that a go. Thanks.

 

[rich1911]

No one mentioned the angle grinder chainsaw yet?!!!

Up a 12m scaff tower, working sideways, with hidden nails in the wood, what could possibly go wrong...

 

[Adam W.]

No one mentioned the angle grinder chainsaw yet?!!!

Or a 2" chisel, but I guess that might be to analogue.

forgot to ask, can you post a picture of the gable ?

 

[Jacob]

Or a 2" chisel, but I guess that might be too analogue.

....

Could a 2" firmer be ground to make it into a shallow gouge? Would leave a beautiful traditional surface finish.
Hand tools definitely the way IMHO. Not least because of the nails etc. Easy to sharpen chisels (as long as you aren't into modern sharpening fashions).

 

[gregmcateer]

I'd is a multi tool if you've got one. A bit tedious, but very controllable

 

[Woody2Shoes]

I'm not answering your question (!), but just checking - are you sure that this timber is not structural (ie holding part of the roof up)?

I would be tempted to replace the whole thing (and probably the rafter/bargeboard above it).

 

[pe2dave]

I note you made a steel support / cage for the router? How about
two lengths of wood, run the router as you do with the steel?
Cruder methods aren't likely to leave you a decent flat surface to which you could fix a supporting piece of wood?

 

[rich1911]

Or a 2" chisel, but I guess that might be to analogue.

forgot to ask, can you post a picture of the gable ?

Here's what I'm dealing with.

 

[rich1911]

Could a 2" firmer be ground to make it into a shallow gouge? Would leave a beautiful traditional surface finish.
Hand tools definitely the way IMHO. Not least because of the nails etc. Easy to sharpen chisels (as long as you aren't into modern sharpening fashions).

The surface finish is not important as it will all be covered with new boarding, BUT where I need to lay new wood onto the original beams, I want as flat and level (as in vertical, horizontal and in depth) as possible. The construction means that only the beams running across need all the work. The uprights and diagonals are easily completely replaced.

 

[rich1911]

I'd is a multi tool if you've got one. A bit tedious, but very controllable

I'm thinking I may route out every other 15mm and chisel or multitool out the remaining sections. That way the jig keeps the surface dead flat and level and I have a good guide surface for the multitool. This would almost half the time it takes to do.

 

[Jacob]

Looks a nightmare!
What about just covering the whole surface with horizontal shiplap or feather boards? Job done in day!

 

[rich1911]

I'm not answering your question (!), but just checking - are you sure that this timber is not structural (ie holding part of the roof up)?

I would be tempted to replace the whole thing (and probably the rafter/bargeboard above it).

The construction is two cross beams. The lower sits on the ends of the ceiling joists. I'd say it is defo structural. Above it is another cross beam, this is suppoted by short uprights, about 5 or 6, which sit on the lower beam. These uprights can be replaced, one at a time with new wood.

As the rot has only gone into the cross beams from 0mm to 30-50mm in the worst area, there is still a good 50mm of solid wood remaining in the worst part. I'd like to repair it in situ rather than take the whole dormer apart and strip off the roof tiles etc etc. by removing all the rot, replacing with new timber and possibly bolting on a steel plate or a second beam to the back, just to make sure it retains its integrity. There's not a massive amount of weight on it though...

Obviously the rest of the dormer roof is supported by rafters all the way along. The rot is confined to the outside edge of the frontage timber, because it started on the back of the outer cladding that was put over the frontage a few decades ago.

It's possible that I could just build another frontage, just behind the rotten one to support the dormer gable, from inside the loft and then remove the rotten beam and replace the whole thing.

 

[rich1911]

Looks a nightmare!
What about just covering the whole surface with horizontal shiplap or feather boards? Job done in day!

Well it was covered before - but the cladding was totally rotten. So I need to cut out the rot that's in the beam, treat it, then replace the missing area with new wood. Then I can re-clad it with boarding, but this time with some ventilation from underneath!

 

[rich1911]

I note you made a steel support / cage for the router? How about
two lengths of wood, run the router as you do with the steel?
Cruder methods aren't likely to leave you a decent flat surface to which you could fix a supporting piece of wood?

I used steel to avoid flexing when routing (which would give me a wavy surface finish) and as the beam I'm bolting it onto is not flat due to the rot, I want to support the jig at the ends only. I've got limited depth to play with too. The steel works great but to do a longer version I will need to swap to angle to keep the rigidity.

 

[Jacob]

If you clad it properly with shiplap and allow for ventilation behind, the rot will dry out and stop. Perhaps roughly hack away the worst of it just in case.

 

[Inspector]

Consider screwing a baton of wood top and bottom of the beam edges just thick enough and shimmed as required to ride the router base on, extending the base with plywood if needed. Much like your steel jig now. Use a bearing over pattern bit (eg. Freud 50-106 3/4-Inch Diameter Top Bearing Flush Trim Router Bit 1/4-Inch Shank | eBay ) and hog out most of the wood, the top bearing stopping you from cutting the baton. When done you will have strips of wood along both beam edges that you can remove by the multi tool flush saw, another board screwed on the newly cleaned beam using the router along it to eat the edges or hand tools as you see fit. Now you have a flat surface that you can glue your wood of choice to with your favourite stickum stuff and some outdoor rated screws (deck or stainless) to clamp it. It has the advantage over the steel jig of being easier to set up in place by yourself. You can rout in short sessions so as not to get fatigued and everything stay aligned. The surrounding wood and siding/plaster remains undisturbed. You had the right idea but making a big steel jig to do everything in one go is problematic. Using the house with a little added wood as the jig will be better if you choose to do it with the router. You might want to get several of the router bits in case you missed a few nails/screws. They will come in handy down the road or if you can get them locally return the unused ones. You don't want to blow up the one and only on a Sunday.

Pete