Tip for aligning router guide bushes

[Anonymous]

Hi all

I posted this in answer to a question but thopught it worth repeating here as a useful tip

My tip for ensuring perfect concentricity between a router cutter and guide is one I used on my first router quite a few years ago.
I nipped to my local machine shop (very helpful people engineers) and asked them to turn a stepped piece of steel for each guide bush I owned. One end was turned to either 1/4" or 1/2" and the other a nice 'snug' fit inside the guidebush.

Lock the steel guide pin in the collet and then bolt the guide bush onto the router after sliding it onto the alignment tool.

Voila PERFECT alignment every time :shock:

Cost of this work was wery small, about £10 for 3 different sizes which I guess is a huge saving on the Trend?

Blutack in photo is to hold guide and alignment tool together when not in use.
The guide bush in the picture was made by same firm as I couldn't get the right sized bush for my dovetail jig that would fit my first cheap router.

Cheers

Tony

 

[Chris Knight]

Tony,

I think this is a good idea but I am puzzled as to why it works as well as it apparently does.

I find so often that bolts (or screws come to that) that have a countersunk head, impose their own logic on whatever you are trying to fix as the angled bit of the bolt head, enters the hole, it forces the hole to be concentric with itself and, in the case of a guide bushing, it thus forces the whole thing off line. I can see that your centering thingies hold the guide bushing firm whilst they are in place but what happens when you replace them with a bit?

I have a predecessor of the Trend unibase, which is similar except that it only fits the Dewalt holes. This is attached to the router base with flat head bolts rather than contersunk heads but since the holes for these bolts are larger than the bolt diameters, there is a risk that the whole base can shift.

I really haven't found an answer - which I consider a shame. I would like to use guide bushings more than I do but I have terrible trouble getting them truly concentric. When I do use them, I make sure to keep the router facing the same way, so then at least I know in which direction the cut is displaced.

 

[DaveL]

I have a predecessor of the Trend unibase, which is similar except that it only fits the Dewalt holes. This is attached to the router base with flat head bolts rather than contersunk heads but since the holes for these bolts are larger than the bolt diameters, there is a risk that the whole base can shift.

Chris,

I have the Trend unibase and it relies on the flat head bolts to allow you to centre the base. The bushes are then held with counter sunk screws, guaranteeing the position of the bush to the base. Did I explain that properly, I'm not sure.

 

[Chris Knight]

Dave,

Your explanation was clear. I guess I am just suspicious of the friction of the flat head bolts doing the job in a critical situation - looking for something a little more positive I suppose.

 

[Newbie_Neil]

Hi Chris

My first router was a Trend and since then I have bought one of the Trend guide bush sets.

For each job I always look to see how I can use a guide bush, as it makes routing so much more accurate.

Cheers
Neil

 

[Anonymous]

Tony,



I find so often that bolts (or screws come to that) that have a countersunk head, .

Hi Chris

Good point, however I have owned 5 routers and only one of them has countersunk screws holding the guide bush on. I find that once set with my little pin and with bolts tightened quite firmly, the guide bush does not move and is perfectly centred.

If you find the guide moving around under flat head bolts as you alluded to in your psots, then you might find the addition of 'star washers' might help if there is enough depth in the counterbore to lallow them to be fitted.

Cheers

Tony

 

[Chris Knight]

If you find the guide moving around under flat head bolts as you alluded to in your psots, then you might find the addition of 'star washers' might help if there is enough depth in the counterbore to lallow them to be fitted.

Tony, that is a very good idea. I shall now kick myself for not thinking of it myself.

 

[RogerS]

Do folks cut down the Unibase? Seems to me quite large and if fitted to a smaller router then the size might get in the way? Or am I worrying unnecessarily?

 

[Philly]

Hi Roger
Yes, I trimmed mine down when I fitted one to a B+Q router. Also worth checking it is flat too-mine had a little bit of "flash" that needed smoothing to make the base perfectly flat.
Cheers
Philly

 

[Newbie_Neil]

Hi Roger

The question you should be asking is, why do I have to bother with a Unibase? The answer is that you do not.

Have a look here at my post.

The Leigh attachment fits into the router and you do not lose the outline of your router not the 8mm depth of the unibase.

Cheers
Neil

 

[RogerS]

Hi Neil

Yes..I saw your post and a great tip....but unfortunately I've already got the Unibase!

Cheers

Roger

 

[Steve Maskery]

This really is a problem isn't it? Even on high-quality routers (I have an old Elu177E, A DW equivalent (625? from memory?) and a Trend T11 and none of them are perfect. I recently inlaid a million ellipses with stringing(at least, that what it felt like), and even with the best set-up I could achieve some of the stringing was a bit loose, relying on glue rather than fit, because I had to go round a couple of times, and the path was ever-so-slightly different.

The T11 comes with a centring tool for the default 30mm bush, but it's a pain if you have to get one made for every different bush. Perhaps the Unibase would be the answer to my dreams?

Cheers
Steve

 

[ivan]

I've recently bought a Trend T10/11 adjustable guide bushholder (accepts the standard range of Trend GB bushes) as a spare part, £4.50, because it will also fit my DW625 (and presumably the CMT clone too). This fits inside the cut out in the router's base, and doesn't rob you of any plunge depth.

Once the bushholder is loosely fitted to the router base (panhead screw in oversize holes), you firmly fix with coutersunk screws, the bush that matches your line up pin. With the latter in the collet, you can then centre the holder/bush combination, which is held in place by tightening the pan head screws. Once you've done this step, because the GB series bushes have coutersunk fixing holes, any bush from the set (from 10 to 40mm) will be concentric with the cutter, without further lining up.

This bushholding part, which Trend call an 'Adjustable inner Plate' is pictured on page 103 of their current Catalogue. With some careful filing, it will work on theDW621 also. Thus you can have accurately centred bushes without having to fit a Unibase.

Where more support is needed, the much larger Trend 'Square Sub-Base Set' can be accurately lined up in the same way, but you do loose plunge depth with any below the base sub-base.

 

[Newbie_Neil]

Hi Ivan

Welcome to the forum.

Cheers
Neil

 

[Adam]

Thanks for the comments Ivan, and welcome to the forum.

Adam