Glulams: cutting and drilling them

[ToughButterCup]

Our Glulam needs to be joined to our steels using this plate.

 

The Glulam needs a slot cutting in it and holes for the bolts, therefore. The plate is 8mm wide.

 

Do the slot and the holes have to be made in the factory, or can I drill and cut the slot myself?

[Construction Channel]

I can’t see why you couldn’t. Take a scrap of wood up the top. Clamp it where the glutamate will end, drill through the holes, “should” be the perfect template. 

 

Cut the groove with the chainsaw and refine with a chisel. (Half joking, it will be much more accurate with a skill saw if you can cut deep enough.) 

[joe90]

I have cut slots in Glulams before and drilled holes. I do have a large circular saw tho?!,  best to measure at least three times or use C.C. advise above , drilling at exactly 90’ can be challenging.

[MikeSharp01]

If you want a toy that makes this easy have a look at this:  http://www.powertool-supplies.co.uk/festool-sword-saw-ssu-200-eb-plus-gb-240v.html?gclid=EAIaIQobChMI-rKK3tGK2gIVbgDTCh2Q1gDzEAQYAyABEgKFtPD_BwE other vendors are available.

 

[MikeSharp01]

PS think I might want to 'speak' to the person who ran that weld down the plate joint, probably the apprentice on a Friday!

[Russell griffiths]

If you make a template lay it on both sides and drill from both sides, that way if you are not at 90degrees with your drill bit it won’t come out the other side in the wrong place. 

[ToughButterCup]

11 hours ago, MikeSharp01 said:

PS think I might want to 'speak' to the person who ran that weld down the plate joint, probably the apprentice on a Friday!

 

Yes, @MikeSharp01, that had not escaped my notice either. There are other welds that are similarly poor. Me being the expert welder an' all !

 

For those in the North West of Lancashire who might need some steel work done, PM me for the name of the  company to avoid. This isn't the place, but I wouldn't want any others on BH to be similarly disappointed.

[dpmiller]

what's the other side of the plate like? The penetration looks dangerously poor on that side.

[ToughButterCup]

1 hour ago, dpmiller said:

what's the other side of the plate like? The penetration looks dangerously poor on that side.

 

Right. That'll do for me.  Thanks @dpmiller

When the rain stops, I'll go and photograph the other side and post below.  Everyone who knows anything about welding - and who has commented - has had nothing good to say about the quality of many  welds on this job. The apex weld (the one shown above) was done in the workshop. 

 

How does someone like me (a beginning, infrequent hobby stick welder - famously dubbed by @Declan52 a 'braille welder') judge the quality of a weld?

 

Or more accurately, when should I reject a weld? I am aware of the arguments about Domestic Customer and so on... 

But the issue comes down to, for something as minor as this (we aren't talking about welding in  a jet engine)  '... Who should check this weld to ascertain that it is of a sufficiently high quality to do the job?..... 

That said, I have seen some beautiful welds (since I started dabbling) To an extent, I think I can recognise excellence - on the surface of a weld at least. 

[dpmiller]

Look at the region between 18 and 21 as an axample, the bead looks like it's just sittng ON the surface. Not hot enough to melt the base metal. You want to see a smooth transition for base to filler, possibly even wth a narrow dip where the base has melted.

 

Have a look at the other side, and if it looks anything like that, whack the plate with a lump hammer and see if the paint cracks over the welds.

[ToughButterCup]

3 minutes ago, dpmiller said:

[...]

Have a look at the other side, and if it looks anything like that, whack the plate with a lump hammer and see if the paint cracks over the welds.

 

... and photograph it before and after. 

Posts like yours keep me coming back to BH. Thanks very much indeed.

Ian

[StructuralEngineer]

The weld looks poor but will hold.

 

The glulam connection on the other hand, with just one row of bolts... has this been checked by anyone? I mean that sincerely.

[StructuralEngineer]

My gut said that connection didn't look right. I just did a quick search and found this:

[ToughButterCup]

Hmmm, @StructuralEngineer

This is the sketch our SE gave us ( posted here as an annonymised image), and the steel erection company  appears to have followed that....

 

 

and this is (verbatim) the email from our SE

'... 

The spacings between the 4 holes appears to be 50mm from the photograph, where 48mm is the minimum requirement, so it’s ok in that respect. The top hole is the only questionable one, where again, 48mm is the min. required distance between the centre of the hole and the top of the glulam beam. So, it all depends on where the top of the glulam beam is relative to the top hole. It’s hard to judge this from the photo. Perhaps, the glulam can be located slightly higher up than the plate to ensure this 48mm distance is achieved? If not, then the plate could be cut off and relocated further downwards.

So overall, the plate is fine, but it may have to be repositioned in order to achieve the required distance between the top hole and the top of the glulam beam. ...'

 

As written, I conclude that the key issue is the distance from the top of the Glulam to the center of the first hole. So, I will double-check that when the rain stops, and post the result.

 

Your post, @StructuralEngineer is interesting. The idea you cite seems to me to be analogous  to a joist hanger.

The single glulam (270 by 140) covers two spans

• one just under 3 meters to a central concrete pillar,
• and then a further 4 meters or so to the other edge of the ridge. 

To be clear, I am not asking you for a professional opinion. I am also aware (from direct experience in this build)  that SEs faced with the same building problem come up with different answers. 

 

It seems I have a choice now. Interesting this self-build lark innit?

 

 

[StructuralEngineer]

The detail (from Structural Timber Association) is suggesting a single row of bolts is bad practice as it can cause splitting, and that they prefer to see a bearing plate under the glulam beam.

 

For example like this:

 

 

Typically also glulam connections will have multiple bolt rows, any number of which can be seen here: https://www.pinterest.com/pin/294493263104077506/

 

 

[ToughButterCup]

Yes @StructuralEngineer.... my finger-tips tell me you are likely to be correct. And more to the point, your point needs careful consideration because of the evidence you bring to the discussion.

 

I sense a delicately worded conversation with the SE coming on. 

Could you bear posting a few references that are accessible online , please?  That way I can pretend that I found them for myself and start a professional conversation.

 

Whats needed here is  a blend of your idea with the one that our SE has proposed. And that shouldn't be too hard now should it?

 

 

[StructuralEngineer]

3 minutes ago, recoveringacademic said:

I sense a delicately worded conversation with the SE coming on.

I'm sure it'll be fine. You could always go along the route of "you're right about that top bolt spacing -- perhaps we can go with a plate under it to be sure?". He/she is probably as worried about it as you are.

 

Looks like the document is freely available: http://www.structuraltimber.co.uk/assets/InformationCentre/eb9.pdf

[ToughButterCup]

1 minute ago, StructuralEngineer said:

[...]

He/she is probably as worried about it as you are.

[...]

 

Simple professional concern.

I'll sell it as  '... belt and braces approach.... ' If that approach works for @Nickfromwales, it'll work for us.

 

Thanks. Slightly easier night's sleep ahead, methinks.

Ian

[MikeSharp01]

On our build we have had THESE from strong tie specified. I think they use pins rather than bolts but single row all the same. 

[SteamyTea]

@recoveringacademic

You should have a read of our old mate Ed Davies blog, he has similar issues.

https://edavies.me.uk/2015/09/drill-test/

Re the welding.

Remember that bit of uphill I did for a laugh.

 

Edited March 27, 2018 by SteamyTea

[StructuralEngineer]

13 hours ago, MikeSharp01 said:

On our build we have had THESE from strong tie specified. I think they use pins rather than bolts but single row all the same. 

Thanks @MikeSharp01 for the link. These look like they can take about 12kN safe working load for 4 holes and 120mm long 12dia steel dowels. Is that round about the load you have? @recoveringacademic

[ToughButterCup]

Not sure @StructuralEngineer, I'll dig around and find out.