Hi Michel

I have restored penetration of newel posts by all the relevant steps and gone through all components till I am satisfied with them. I offset the tenons which meet in a post by a certain amount to bring them higher or lower (posts 1 and 4. Post 2 has stringers arriving at different heights anyway). I have done this even though I am not convinced it will help much. It is by cutting the fibres across the grain that the wood is weakened most, and that has already happened as soon as you cut out the long mortice.

One good thing is that most of the pressure is downwards where there is plenty of wood, and if I can do the joints nice and tight, then there will be wood there from the joining members to add support. I did reduce the tenon thickness to 25mm from 30mm but I kept the tenon penetration at 50mm for reasons i explained earlier.

Anyway, I have attached the latest design. By all means check that there are no glaring errors or impossible joints and if it looks OK to you then please generate the cutting list. I am keen to see the measurements so I can check that all the joints will be sound and strong.

Thanks a lot

Andy

Hi Michel,

I think I did say that I wanted to keep the stair as wide as possible, given the constraints. The reason is that 740mm of tread is already not very much for a main stairway.

I see that you have offset the handrail with reference to the stringer and that, as the banisters are centred on the handrail, they stick out of the side of the stringer. It looks like I will have to manually adjust there.

Could you please confirm that what you have done on the treads is to reengage them with all the newel posts. Yes, that is why I simply cut around those newels where I judged there was already enough support from the stringers. Making those cuts, especially with shoulders all round, will be more work, as you say.

Why did you do this? Is there some structural reason why the treads should engage with the newels? It would be good to know why it is imperative before settling on this solution.

The reason for having 50mm tenons on the stringers is that when using draw pins, there needs to be a bit of ‘meat’ in the tenon to prevent the end breaking out, for the pin to push against so that it effectively draws the tenon inside and forces the shoulders to rest against the sides of the post. Conversely, there must also be enough ‘meat’ between the holes for the pin and the wall of the post for it to resist and bend the pin without the wood breaking out. A weak pin of 6 or 7mm width will not bring the tenon in. A more sturdy one of 13-15mm will. But it needs support.

If I reduce the penetration to 40mm, then I don’t get that ‘meat’. I might as well reduce it to 30mm bolt.

That is the reason that I made the posts, not 90mm, but 110 and 120mm square. I could reduce the thickness of the tenon to 25mm perhaps…

If you could come back with answers to these questions, I think I could make some decisions and we might try for a first cut of the list of cutting materials so I can review it.

Get back to me and I will do ‘my’ final version so you can generate it.

Cheers

Andy

Hi Michel,

Yes, thank you for your help on this. In the meantime, I have done some work on the stair.

I have shortened the whole of flight #2 by 30 mm to accommodate a 30mm plate to be bolted to the ends of the stringers and to the face plate at the top.

I have removed tread joints to the newel posts where I think I do not absolutely need the support. This simplifies the cuts.

I have changed the stringer tenon penetration back  to 50mm. I am comfortable with chopping the mortices out and that some draw pins will provide good support. If I find them at all loose I can still drill and screw from behind if I can get there from behind the big kite steps.

Tread penetration at 20mm.

The more complicated steps are 1, 3,4,5,6 and 15. It might be worth you having a look.

It appears to me that the software will not allow the handrail to be offset with reference to the newel posts. It is always fixed with reference to the stringer to which it is connected by the banisters. Is that true?

As I told you, I have to move the handrail away from the wall for most of flight #2 as there is currently only 15mm clearance from the stringer which is not enough. Could you confirm that the thickness of the handrail is actually the depth and that it is currently set at 50mm and the width is 40mm. If that is so, I have 22.5mm of clearance between handrail and wall. Still not enough. I would like to move the handrail and its joins with the 2 newels and the stringer(by virtue of the bannisters) into the staircase by 7.5mm.

Please tell me if the software cannot do it so I don’t spend any more time on it. And I will think how to compensate manually.

Cheers

Andy

Hi Michel.

Yes, step 6.

OK, I am going to spend the morning trying to get the design the way I want it, incorporating these ideas, and I will send it to you tomorrow afternoon. If you could check it, that it works and that it can be installed, I would be grateful. CAD we can do later if it is required.

Cheers

Andy

Hi Michel,

OK let’s say 20mm for the tread stringer penetration.

How I had envisaged attaching flight #2 to the face plate at the stair head was like this: I would like to shorten the available length from 3149mm to 3119mm so that I can bolt on a riser of 30mm thickness that can be in turn bolted to the face plate. This means that it may be necessary to cut off some of the 2 stringers at a height of 3029mm minus 21mm for the floor so that the string will sit up against the overlapping floor above. Can this be done in Stairdesigner? Is it possible to keep in stairdesigner a riser (without the following tread) of 30mm thickness and width which goes down to the bottom of the string width as it hits the face plate? Can that be done? Really I would like a piece of wood 30mm thick and 850mm long which is as wide as the stringers are when they hit the stairhead. That is what is ideal. If it is difficult to design then I can shorten the run by 30mm and just remember that I have to attach this plate at the end. It will have knockon effects on Newel post 5. Not sure what effects just yet.

As far as that is concerned, I think the handrail has to be offset otherwise it will be too close to the wall for people to use it for the first 2 or 3 metres. It means it has to enter newel post 5 at an offset, and newel post 2 at an offset but not so much that he thinnest member, at 55mm, right stringboard #2, cannot accept the spindles Currently with stair width of 850mm there is only about 15mm clearance between the right stringer and the wall. If we were to centre the handrail over the stringer then we would have only 2.5mm(half the difference between 55mm and 50mm ) plus the 15mm, so  only 17.5mm clearance between handrail and wall. This is obviously not acceptable for use so we need to gain another 15mm or so to get a clearance of 32.5mm for people’s hands to pass behind the handrail. This will the spindle will enter 10mm from the inside edege of the stringer which I think is OK. I am not sure if I can do this in Stairdesigner.

The other matter for concern is step #7. I do not want it penetrating the flight#2 stringers at all as it will interfere with installation.

If you remember, I plan to build the stair in 2 parts for ease of installation. That is why I wanted newel post #4. Is it possible to play with the recess variables to prevent stair#7 from penetrating the flight 2 stringers?

Sorry there are more questions.But better now that after I start cutting.

cheers

Andy