Fine height adjuster for Bosch POF52/500A and similar

[baldpate]

Hi,

I've just got Rob Wearing's book on "Router Tips and Techniques". I notice he has a a Bosch POF52 (shown in a number of illustrations), above the left hand plunge column of which is affixed what looks like a tube surmounted by a knurled knob. The function of this accessory isn't described, but I'm wondering if it is a fine-height adjuster.

I've got a POF500A. I've been pondering for a while how best to make a fine adjustment device for it (the M10 depth stop assembly is a little coarse for this purpose, for my taste) The plunge column on the POF500A which corresponds to the POF52 column has a short M6 threaded hole at the top, onto which a washer is held by an M6 bolt: this stops the motor assembly lifting off the plunge base !.

I'm prompted by the photo in Rob Wearing's book to wonder if this threaded hole can be used to make a fine-height adjuster - indeed, whether the device shown in Rob Wearing's book is just such an adjuster.

Can anybody assist? Is such a device commercially available for this router type? Am I right in thinking the pictures in RW's book do indeed show a FH adjusted? Have any of you made, or used, such a device for this type of router.

Thanks for any info you can give me.

Chris

 

[jimi43]

I don't know if this helps but I built a powered router lift based on a similar AEG to the POF50....it's basically the same...

I attached a fine screw to the height stop which was threaded to suit:

The rod runs on a top bearing and one revolution raises the bit less than 1mm:

Obviously you don't have to go to this extreme as this was for a special job but the rod can just be fitted with a knob on the top to turn by hand.

You don't need all the ply bits either...this is done to mount the router lift motor (ex power screwdriver)....

Here is a close-up of the working end...

UPDATE...

I just dug out some pictures of my router thicknesser which is actually a POF50 and on that I used the same fine adjustment...

....it's the threaded knob just behind the dial gauge:

So it can be done this way.

Hope this helps...


Jim

 

[9fingers]

A tip for POF xxx router users.

The locking mechanism only works on one side and under heavier cuts can allow the bit tomove with respect tot the base.

Unscrew the locking knob and look at the the little brass slug underneath. make another one the same from brass (or aluminium if you don't have any brass to hand). Unscrew the other knob and insert the new slug.
Voila! locking now works on both sides.

Bob

 

[baldpate]

@Jim - thanks for the reply and the pics. Your AEG has what I would call the 'standard' depth-stop arrangement (plain rod running through hole in router body, dropping onto three-position threaded turret on base, with thumbscrew into body hole to fix rod at required position) which lends itself to the sort of adjuster you've made for it (nice set-up, by the way!).
Unfortunately, as you know, the smaller Bosch POFs use a different depth-stop system, using an M10 threaded rod through a hole in the motor housing (with a threaded detent, for quick positioning), dropping onto a plain, unthreaded boss in the base. I presume your POF50 has the same system. I'm afraid I can't quite work out from the two pics of your router thicknesser how your FH adjuster works : how does it attach to the base? Are you using the M10 depth-stop hole? Did you have to modify the metalwork off the router base or body in some way?

@Bob - neat trick, I'll remember that one!

Any other ideas for a FH adjuster on a small Bosch??

 

[9fingers]

If you can find a tube with 12mm bore (I think), then remove the M6 screw from the top of the pillar and insert a length of M6 studding and slip over the tube and with some bodging washers and a nut, you can lower the router by 1mm for every turn of the nut.
If you have a metal lathe, then some nice parts, spacers and a calibrated knob can be turned up to have the same effect.

All depends what you have available.

Bob

 

[jimi43]

I think Bob has described it exactly BP....I am off to work at 2pm but will try to post some other pictures or take some more later, maybe tomorrow. Those pictures are a while back when I was making some special jigs...

The Bosch 900 I have has a fine adjuster which looks like this:

Of course that's the "big daddy" but the principle is the same...the knob at the top rotates on a fixed collar which lowers the whole router a tad each time.

This is the method you need to adapt your router to...depending on what you can use or modify to achieve this. Some pictures of your setup might help...

Jim

 

[9fingers]

Those members of the 900/1200/1300 family that offer the fine adjustment have a cunning scheme that interacts with the main locking mechanism. You can 'fast forward' to the nominal position with the main lock released and then once locked, the knob will adjust it plus or minus a gnats tadger from the locked position. This would not be easy to do with the older models.

Bob

 

[baldpate]

Thanks again to both of you, that's clearer now. I think what Bob is describing must be what I saw in the pictures in Robert Wearings book. Now that you've set me on the right track, I'm off to the loft workshop to see what I can knock-up - I'm pretty sure I've got all the necessary bits and pieces somewhere, or at least ernough to bodge something up.

If it works, I'll post some pictures later on (presuming newbies like me are allowed to do that).

Thanks again.

Chris

 

[Eric The Viking]

The locking mechanism only works on one side and under heavier cuts can allow the bit tomove with respect tot the base.

Good idea Bob. Miles Tools have the correct slugs as spares (always buy two!), also 8mm collets in case you're feeling continental. I take the springs off to minimise the effect usually, but I agree that it does move about a bit.

The thing I can't do is stop the plunge mechanism jamming up. I even 'invested' in a new plunge base and clamp assembly, but that didn't help. I wish I could find a good lubricant, but so far I haven't.

I still think it's a great little too though. I've had mine for about 15 years and it's still going strong.

E.

 

[baldpate]

Here we go - I think this is what Bob meant. I've taken a series of pics to show how the adjuster is built up (in case it helps any other beginner like me to see it in stages).

1. A short length (about 13 or 14cm) of M6 threaded rod is screwed into the threaded hole at the top of the plunge rod, and locked in place with a nut over the original washer (which prevents the motor housing coming away from the base).

2. I had some thin-walled alumium tube which fits snugly over the outside of the upstanding part of the casting which houses the plunge rod. I cut it to 10cm. so the threaded rod projects a few centimetres above it.

3. A big washer and a substantial nut completes the most elementary version of the adjuster. Turning the nut clockwise pulls the M6 threaded rod up, and with it the plunge rod, so 'plunging' the router.

4. However ... to make it easier to operate I replaced the simple nut in pic3 with a long, hollow 'handle' which has an M6 threaded hole at the bottom end and a knurled knob at the top. The knurled knob at the top rises above the level of the motor housing, making it easier to access and turn.

It looks as if it will work pretty well, though I haven't tried it in anger yet. There are a couple of minor drawbacks :
(a) As Bob noted, there's no 'fast-forward', so you have to wind it all the way down to the desired position.
(b) While this mechanism, of itself, prevents the collet/bit from rising should the plunge lock be accidentally released, but doesn't (as do some FH adjusters) prevent the collet/bit from being plunged deeper. However, this can be quite easily prevented using the depth stop. Putting a lock on both handles, as suggested in an earlier post, wouldn't be a bad idea either!

Thanks again for your patient help.

 

[Davef]

Hi

This may be of use to you. I made one from brass works a treat.

Dave