What router bits do I need for this job?

[mrodent]

I live in a 1930s house in the UK with all the original windows (single glazed). All the windows are wooden casements (although a few are "faux casements": they look like the real opening casements next to them, but in fact don't open).

I'm planning to replace all panes with vacuum-glazing (a form of double glazing) panes and also add some bulb weatherstrip in a groove to help with both noise and heat insulation. A first set of vacuum panes are on order and will be delivered in March.

I've bought a router (Makita RT0700CX4, 710W) and am a total newb when it comes to routers. I have a very healthy respect for this machine and the damage it can do. Plan to learn as much as possible and then practise on waste wood. Also plan to build a basic router table for clamping to a workbench (many examples at YouTube).

1. Cutting a very narrow groove for bulb weatherstrip
The weatherstrip grooves (to be cut on the side of the frames, obviously) need to be about 3 mm wide. I think the recommended thing here is something like this. But I'm also aware of these "groover" bits, such as this. In the latter case I believe the router would be moved along the top of the window, with the cutting blade cutting into the edge. Which type should I use?

2. Machining the rabbets on the frames to accommodate the new panes
The thickness of the existing glazing is probably about 3 mm. The vacuum glazing panes will be 8.3 mm thick.
This means that the rabbets on the outside of the casement frames (i.e. once I have removed the putty and existing pane) will have to be made deeper. But the area in which the new panes will sit will probably also be slightly wider, because the edge beyond the sight lines of the new panes is 10 mm all round (NB inevitably these panes are much heavier than the existing ones).

So what sort of router bit should I looking at in order to both deepen and widen the rabbet groove holding the panes in the casement frames?



Hope all the above makes sense...

NB The router manual seems to suggest that either metric or Imperial measurements of the shank diameter are acceptable! I contacted Makita UK 2 days ago. According to the Makita UK technician you should use Imperial diameter bits with this router (1/4" or 3/8"). Probably pretty important. Recommendations re brand would also be helpful. Carbide bits seem to get a lot of thumbs up.

 

[Doug71]

It isn't easy putting a groove in the frame with a router as you can't get right into the corners. There is a special tool for it but not cheap!

https://www.scosarg.com/virutex-ra1...lLXTU1WpkwM-raf8-N2Wf5ItxmUzbZwEaArJ8EALw_wcB
I have put the seal in the sash before using a wiping seal like AQ21 and a cutter to match.

https://www.reddiseals.com/product/schlegel-aquamac-21/
https://www.axminstertools.com/axcaliber-weather-seal-cutter-for-aquamac-21-wiping-seal-666074
Edit Just realised it's a 1/2" cutter I have linked to but you wanted smaller

 

[Derek Cohen (Perth Oz)]

I would get a plunge base for your router, and use the first bit. It does not need to be a compression bit - these are pricy - a 1/8" spiral downcut would be as good and cheaper.

The rebate is best made with a set, such as this ..

The collars allow you to move deeper without taking too much off in one go.

Regards from Perth

Derek

 

[Fitzroy]

Nothing to add except my interest. Which vacuum glazing system did you go with? Are you willing to share your experience on ordering and costs? It’s one of the options I’ve been considering for my old single glazed sashes.

 

[mrodent]

@Fitzroy ... did quite a bit of research into this and the best brand appears to be LandVac. www.landvac.net. I found somewhere some analysis which suggested that 8.3 mm LandVac vacuum glazing is equivalent to TRIPLE glazing in terms of heat (and noise?) insulation.

I eventually found the UK supplier ... Ring Tony Dee at Grosvenor Restorations: 07830 095189. 12-week lead time from order. I was actually pleasantly surprised at the cost, at least when compared to getting someone to *replace* otherwise perfectly good windows! NB as I say, mine are all casements... but there are many guides out there about belt-and-braces insulation of sashes.

 

[mrodent]

It isn't easy putting a groove in the frame with a router as you can't get right into the corners. There is a special tool for it but not cheap!

https://www.scosarg.com/virutex-ra1...lLXTU1WpkwM-raf8-N2Wf5ItxmUzbZwEaArJ8EALw_wcB
I have put the seal in the sash before using a wiping seal like AQ21 and a cutter to match.

https://www.reddiseals.com/product/schlegel-aquamac-21/
https://www.axminstertools.com/axcaliber-weather-seal-cutter-for-aquamac-21-wiping-seal-666074
Edit Just realised it's a 1/2" cutter I have linked to but you wanted smaller

Thanks for these suggestions.

In fact when I talk about cutting a groove for the weatherstrip I'm talking about cutting it in the *outer* frame of a very simple casement frame, with no complicated rabbets as you get on so many proprietary window systems, so there won't be any inner corners involved with that job. Something like that Aquamac bit, but with a 1/4" shank, looks like the right kind of thing.

Conversely, regarding the other job, widening and deepening the rabbet to accommodate the thicker, wider vacuum glazing panes, this *will* involve "inner corners", and a plunge cut with the router. I am currently assuming that I shall just finish off the corners manually: I'm fairly handy with wood carving. Any recommendations for the best bit there? Derek's recommendation of graduated collars seems to make sense.

 

[mrodent]

I would get a plunge base for your router, and use the first bit. It does not need to be a compression bit - these are pricy - a 1/8" spiral downcut would be as good and cheaper.

The rebate is best made with a set, such as this ..

View attachment 152611

The collars allow you to move deeper without taking too much off in one go.

Regards from Perth

Derek

Thanks.

Could you just expand on what you mean when you say "use your first bit"... you mean the first bit I included a link to: "compression 1 flute"? Why would it be better to use that than a "groover" bit?

Secondly, this picture you've shown here of the Torquata bit with graduated collars for enlarging a rabbet: is there a name for this category of bit? Or could you tell me the model in the Torquata catalogues? I've been looking but can't find...

 

[Derek Cohen (Perth Oz)]

The "groover" bit requires that you bring the edge of the bit into the wood. This requires that the router is away from the edge of the wood, and it requires to be balanced at a distance to do this. This type of bit is more usually used in a router table. By contrast, the fluted bit does not require the router to be supported, but rather plunged into the wood (hence a plunge router is preferred). There is much more control with a plunge router guided by a fence.

Torquata is a maker not a type of bit. The different collars (rings) are placed on the bit, starting with the largest (which holds the bit furthest away from the wood). The next smaller bit increases the depth of cut. You keep going until you reach the depth you want.

It sounds as if you need to do more research before you are ready to perform any of these tasks.

Regards from Perth

Derek

 

[Thingybob]

I was building replacement sash frames for many years and the idea I came up with was to reverse the idea machine the putty bevel in the frame with the rebate to the inside of the house I used 48mm thick stock allowing 13x13 for the bevel and rebated 35 x13 for double glazed units of 20 mm thickness 2x4mm glass 12mm air gap then beaded with 12mm x 15mm ovolo strip the extra weight meant using spring balances but Mighton do a good range and their parting bead with wings worked fantastic have a look on thier site ps no need for putty so added security

 

[mrodent]

The "groover" bit requires that you bring the edge of the bit into the wood. This requires that the router is away from the edge of the wood, and it requires to be balanced at a distance to do this. This type of bit is more usually used in a router table. By contrast, the fluted bit does not require the router to be supported, but rather plunged into the wood (hence a plunge router is preferred). There is much more control with a plunge router guided by a fence.

Torquata is a maker not a type of bit. The different collars (rings) are placed on the bit, starting with the largest (which holds the bit furthest away from the wood). The next smaller bit increases the depth of cut. You keep going until you reach the depth you want.

It sounds as if you need to do more research before you are ready to perform any of these tasks.

Regards from Perth

Derek

Thanks. As I said in my original post, "am a total newb when it comes to routers." I have an extremely healthy respect for these tools, which are probably among the most potentially dangerous.

But understanding what bit (of the many available) to use for these 2 jobs is not something I can just look up online. Believe me, I have already watched innumerable Youtube vids and have also bought an actual book "Woodworking with the Router" which I'm reading right now.

Consequently I am asking for specific advice here in this forum, which I think is fair enough. I have every intention of building and making a router table in the next couple of weeks, and then gingerly experimenting on lots of waste wood with a couple of high-quality bits to find out what I can and can't achieve (safely!). The potential problem with a 3 mm fluted bit for the weatherstrip groove might be that this is a very narrow bit, so mightn't it potentially break? The groove doesn't have to be very deep, and obviously I would do it in several passes, but even so, mightn't a groover be preferable? And why couldn't a groover bit be used with the router held in a router table?

Wealden does a groover bit which is specifically said to be for making such weatherseal grooves: Compact Groover ... this is one of the most highly-regarded bit manufacturers in the UK.

Concerning the other job, i.e. deepening and widening the rabbet, I understand this business of different collars, but I was mainly asking about what type of bit that was: is it a "rabbet" bit? I.e. what bit category and characteristics are needed to do this job?

 

[mrodent]

I was building replacement sash frames for many years and the idea I came up with was to reverse the idea machine the putty bevel in the frame with the rebate to the inside of the house I used 48mm thick stock allowing 13x13 for the bevel and rebated 35 x13 for double glazed units of 20 mm thickness 2x4mm glass 12mm air gap then beaded with 12mm x 15mm ovolo strip the extra weight meant using spring balances but Mighton do a good range and their parting bead with wings worked fantastic have a look on thier site ps no need for putty so added security

Sorry, I just don't understand what technique you're describing here.

I'm not a wood professional, and will have to be learning on the job as I refit my casements. These are very very simple 1930s casements, with no complicated rabbet arrangement, as you typically find in contemporary proprietary window systems.

These double glazed vacuum-glazing replacement panes which will be delivered in March are 8.3 mm thick, a lot thinner than a typical double-glazing unit. Therefore the intention is simply to take out the existing single-glazing pane, machine out the rabbet (increasing the depth and the width by a few mm all round), and attach the new pane using Hogdsons Heritage Putty (sealant/putty).

So that is the context in which I'm asking for advice about the router bits to use.

 

[Thingybob]

Sorry, I just don't understand what technique you're describing here.

I'm not a wood professional, and will have to be learning on the job as I refit my casements. These are very very simple 1930s casements, with no complicated rabbet arrangement, as you typically find in contemporary proprietary window systems.

These double glazed vacuum-glazing replacement panes which will be delivered in March are 8.3 mm thick, a lot thinner than a typical double-glazing unit. Therefore the intention is simply to take out the existing single-glazing pane, machine out the rabbet (increasing the depth and the width by a few mm all round), and attach the new pane using Hogdsons Heritage Putty (sealant/putty).

So that is the context in which I'm asking for advice about the router bits to use.

Sorry I thought you were remaking frames I hope they are in a good condition but doing that type of routing on an existing frame is difficult most of my frames were remakes for sash or casement

 

[Thingybob]

Are all the windows you intend to re glaze in good condition as you might find the tenon joints at the corners are loose or broke, If you are taking each casement out to work on might be handy to have a blanking board to put in place of the window in case of unforseen problems and bad weather and balancing a router on a window frame edge with a rebate cutter in not easy so please take care

 

[Ollie78]

It would be easier to put the seal in the casements, no fancy virtuex needed as Doug71 suggested. That bit he shows may be available in 1/4 size but if not you can do it with either one small router bit and one large one or a saw kerf and a normal flat bit.
If you go on the schleigel site they have loads of different seal options, some only need a saw kerf.

For routing the rebates deeper the best method (well its really best to just make new casements ) is to make up a bunch of MDF strips 100mm or so wide then make templates with them the sizo of the openings, using mitre mate or pocket screws etc. Clamp the templates over the casement and use a bearing guided cutter to cut out the rebate to depth. In a pinch you can make an L shape and do it in two goes.
Don`t bother cleaning out every bit of putty, as long as the glass is out and try to get all the pins, the router will get it all out.
Note this is very messy, you need to take shallow passes. Buy a bunch of cheapo bearing guided bits from toolstation because they will get trashed fast, like one or two windows max.
Be careful that the joints don`t become compromised and be aware of grain direction, sometimes a climb cut is wise to avoid splitting.
I have used this method on far too many windows to count. Glad I don`t do that anymore.
Definitely wear safety gear.

Just a quick note for that router I think you can get an 8mm collet, if so this opens up different router bit options as this size is quite common in europe and quite a bit stronger than the 1/4 inch. I don`t have that router anymore though, could be wrong....

Ollie

 

[Thingybob]

I have just looked up the router you have and are intending to use for the job in my opinion it's not big enough it's as stated a laminate trimmer might want to rethink the project

 

[Thingybob]

Mr odent if you take a close look at the ones that don't open you might find they once did and have been painted/sealed shut people used to do this to save repairing broken hinges etc I once found that every window in a 1930s house bays and single windows had been screwed into the frames and putty used to fill the crack once painted over it's hard to tell if they opened the same on the inside a close inspection with a small knife carefully will show if that's the case and you will no doubt be painting again so no lasting damage you might get a suprise

 

[mrodent]

Mr odent if you take a close look at the ones that don't open you might find they once did and have been painted/sealed shut people used to do this to save repairing broken hinges etc I once found that every window in a 1930s house bays and single windows had been screwed into the frames and putty used to fill the crack once painted over it's hard to tell if they opened the same on the inside a close inspection with a small knife carefully will show if that's the case and you will no doubt be painting again so no lasting damage you might get a suprise

Thanks, this is really helpful. If these non-opening casements are indeed glued in place I was planning to use a recip saw to extract them. But it had certainly occurred to me that there might be nails or screws involved there, making it potentially quite a nasty job. I think I'm right in saying that screws used to be regarded as rather expensive (pre-1970s?) so I'd be slightly more surprised to find really difficult steel screws used for that job (and which might also damage the recip blades). But I'm pretty much prepared for anything. if it turns out that they are just sealed in place that would be great.

Thanks for the comment about the router I've bought. I could buy a larger one too if this one turns out to be too small. But I'm slightly surprised: all I'm planning to do is shave off a few mm of depth and a few mm of width all round the insides of the outside of the frames. Compared to the budget I'd need to replace all 55 window panes in this house if I was getting some window people to replace them, I can basically afford to buy any number of tools!

Thanks for the safety advice too: I'm pretty sure a router is the most dangerous tool I shall ever buy, and I'll be conscious of that whenever I use it (after reading up on all the safe practices). But again, I've already sketched out in my mind how I propose to rig this up, with sections of wood (or ply) made the same thickness as the frame itself, so I'm not just balancing on the frame ... or possibly even using a router table set-up (disadvantage being that I wouldn't then be able to observe the cutting operation). And everything clamped securely in place.

And yes, I'd already anticipated the need to prepare sections of ply to stick in the windows while processing each frame. I'm starting on the upper floor, so fewer security concerns. The frames (and the fixed frames attached to the building) are in excellent condition, one of the reasons why I thought this was a feasible approach (why destroy perfectly good woodwork and pay someone 10s of 000s of £ to put in new windows when vacuum-glazing, equivalent to triple-glazing insulation, is now an option?).

 

[mrodent]

It would be easier to put the seal in the casements, no fancy virtuex needed as Doug71 suggested. That bit he shows may be available in 1/4 size but if not you can do it with either one small router bit and one large one or a saw kerf and a normal flat bit.
If you go on the schleigel site they have loads of different seal options, some only need a saw kerf.

For routing the rebates deeper the best method (well its really best to just make new casements ) is to make up a bunch of MDF strips 100mm or so wide then make templates with them the sizo of the openings, using mitre mate or pocket screws etc. Clamp the templates over the casement and use a bearing guided cutter to cut out the rebate to depth. In a pinch you can make an L shape and do it in two goes.
Don`t bother cleaning out every bit of putty, as long as the glass is out and try to get all the pins, the router will get it all out.
Note this is very messy, you need to take shallow passes. Buy a bunch of cheapo bearing guided bits from toolstation because they will get trashed fast, like one or two windows max.
Be careful that the joints don`t become compromised and be aware of grain direction, sometimes a climb cut is wise to avoid splitting.
I have used this method on far too many windows to count. Glad I don`t do that anymore.
Definitely wear safety gear.

Just a quick note for that router I think you can get an 8mm collet, if so this opens up different router bit options as this size is quite common in europe and quite a bit stronger than the 1/4 inch. I don`t have that router anymore though, could be wrong....

Ollie

Thanks. Not entirely 100% sure I understand your recommendations about cutting the rebates (I'm not a professional, like so many of the people here), but I think I get the gist: yes, bearing-guided cutter sounds like what I should use.

As mentioned in my previous post, I was wondering whether using a router table might work for this. I'd feel a lot safer using a solidly clamped table, I think. Also, if rigged up with an air extraction setup this would help reduce the messiness. I also intend to box-in and clamp the frame very securely before I do any routing, in order to minimise any threat to casement joints.

I rang Makita UK about the advised shanks for this router. They said that although it says "1/4", 3/8", 6 mm or 8 mm" in the manual which comes with it, they recommend only using imperial gauge shanks (i.e. 1/4" or 3/8"). I've already ordered a couple of bits from Wealden, which may turn out not to be the right ones (I'm going to be doing a lot of practising on waste wood, before I get round to the actual frames).

 

[Thingybob]

Well you seem to have researched the job just take care a bouncing router is deadly as I said before check Mighton site they supply all types of seals for windows and the cutters along with some useful vids and drawings nothing to loose

 

[Ollie78]

Thanks. Not entirely 100% sure I understand your recommendations about cutting the rebates (I'm not a professional, like so many of the people here), but I think I get the gist: yes, bearing-guided cutter sounds like what I should use.

As mentioned in my previous post, I was wondering whether using a router table might work for this. I'd feel a lot safer using a solidly clamped table, I think. Also, if rigged up with an air extraction setup this would help reduce the messiness. I also intend to box-in and clamp the frame very securely before I do any routing, in order to minimise any threat to casement joints.

I rang Makita UK about the advised shanks for this router. They said that although it says "1/4", 3/8", 6 mm or 8 mm" in the manual which comes with it, they recommend only using imperial gauge shanks (i.e. 1/4" or 3/8"). I've already ordered a couple of bits from Wealden, which may turn out not to be the right ones (I'm going to be doing a lot of practising on waste wood, before I get round to the actual frames).

Using a router table will not be practical in this instance. For the same reason its not wise to cut an 8 x4 sheet on a little table saw, but safer to use a track saw, bringing the "smaller thing to the bigger thing" if you see what I mean.
That tiny router is designed for trimming with one hand and is very easy to control.
If you struggle you can make up a larger sub base to help with keeping it flat to the template.

As for the method I tried to explain. Basically you want to make a big square frame, like a flat picture frame. The internal dimension is the same as the rebate for the glass in the given opening. In multi pane sashes or casements you will do each pane one at a time.
You fix this frame to the casement by clamps, screws, pins, or whatever is convenient as long as its secure.
Then you set the router bit to the correct height and route away the wood until its a perfect fresh rebate.
It's best not to try and take a 10mm cut straight away but rather two passes at 5mm for example.

I would not use a decent wealdon cutter for this process. Cheapo ebay ones Erbauer from screwfix or silverline from Toolstation is fine, you will be throwing them out after.
Bits of putty and stuff will ruin them.
We used to use the 19mm ones from silverline. The bearing needs to be on the top end of the bit ( nearest the shank ).
It's pretty easy once you have done the first one.

Ollie