Increase Depth and Width of existing parting bead channel to accept 'reddiseals' U channels

[AnalogKid]

My current Sash parting bead channel / groove are approx 6mm (must be 1/4 inch in 'old money')
There also only 6-7mm in depth
So far I've thinned the edge of 7mm Wood / Brushed Parting beads (from MIghton) to fit

For the reemainder o the SASH's I refurbish; I'd prefer to go down this path

Reddiclip – Parting Bead with Channel

Channel fits into a 8mm wide x 10mm deep groove Channel is pinned into the groove Parting bead simply inserts into the channel and clips securely into place Parting bead will not come out in operation, but can be easily unclipped for renovation or replacement Standard 8mm wide parting bead...

www.reddiseals.com

What method, tool would be recommended to increase the depth and width of the existing parting been 'groove'

 

[fernicarry]

You could try a hand held trimmer router and a straight edge screwed either side to keep you straight. It won't quite reach all the way to the top or bottom so you'd need to finish off by some other means like a hand chisel.

I have the Bosch one and its a slightly scary little beast as it has no speed control and quite a kick when you turn it on. Its handy though for in-situ jobs like cutting slots for weatherstrips etc. Best to start it up away from the piece and then carefully offer it up.

 

[AnalogKid]

@fernicarry - Thanks for the reply .
Using a 'palm router' and Screwing in an edge/jig sounds like the way to go - leaving 2 inches or so at each end that needs chiselling


The photo below is blurry, but shows another possible method for a router that has 'all the attachments;



PS: That photo comes from -

Home Repair Wisdom & Know-How: Timeless Techniques to Fix, Maintain, and Improve Your Home​

and appeared as part of a 'google search'

 

[fernicarry]

The distance from the parting bead to the outside edge of the lining may not be constant so an end fence may not follow the bead slot closely enough. I'd also want to have a guide both sides in case you slip and go the wrong way. Routers are quite happy to chew through just about anything if you give them the chance. It'll be quite an awkward job especially if your windows are very tall so you'll want to arrange comfortable access that allows you to keep the machine well under control.

Are you going to take 1mm off each side of the slot? The will reduce the clearance for the top sash by 1mm plus the thickness of the brush strip. Depends how loose a fit you have to start off with whether that's a problem. If the top sash is already quite a neat fit then you could take 2mm off the inside edge but that will kick everything inwards by the same amount so your staff beads may end up a bit proud of the linings.

I've toyed with the idea of adjusting the width of the staff beads to get them bang on but haven't got to that level of obsession yet....

 

[AnalogKid]

@fernicarry - your suggestion of making a guide would be the best option - and on both sides
I'd initially try to take an even amount of each edge (ie 1mm) - The upper sash(es) have enough 'play' to allow that and I believe I can obtain a slightly shorter 'pile' for the insertable brush strips if that was required
The lower sash should hopefully be fine as well.
Thats the advantage of the 8mm U channel option reddiseals have
They also have a 10mm option - but then we're pushing 2mm on each side and that might be a 'tad' too much

I'll report back with any progress - as I might re-do the parting bead channels on 2 of the WIndows I finished last month
For those Windows - I've not permanently fixed the staff beads in yet - so there's still time to move them slightly to get the right fit
(and fully understand not wanting them to protrude unnecessarily)