So, my trend t4 came with a special hinge jig guide bush...

[cjard]

similar to the supplied 16mm bush only the stem part (if it were a mushroom) is longer and the metal is thinner

Now, the regular guide bush supplied is thicker metal and it fits into the base perfectly wih no slop. It has two countersunk screw holes and countersunk screws supplied

The hinge bush has no countersinking, it just has two slots that are considerably larger than the shank of hex bolts it was supplied with, though smaller than the hex head. It also has a smaller outer diameter than the guide bush so it slops about in the router base and the bolts, being smaller shaft and not countersunk, do nothing to help stop this

I've used the countersunk screws supplied with the regular bush and the hinge bush is now placed reasonably centrally, but it still doesn't seem right. One should not rely on a couple of crappy screws to align a bush; alignment should come from slight interference fit with the hole in the router base, surely.

Any ideas what's the deal? Why would trend supply a guide bush that didn't really fit the router with any measure of accuracy and bolts that don't really fit it, then place all these items in a little bag with a note specifically on it "for greater accuracy when using a hinge jig, use this bush"

 

[Deleted member 174758]

I've used the countersunk screws supplied with the regular bush and the hinge bush is now placed reasonably centrally, but it still doesn't seem right. One should not rely on a couple of crappy screws to align a bush; alignment should come from slight interference fit with the hole in the router base, surely.

No. Read on

Any ideas what's the deal? Why would trend supply a guide bush that didn't really fit the router with any measure of accuracy and bolts that don't really fit it, then place all these items in a little bag with a note specifically on it "for greater accuracy when using a hinge jig, use this bush"

Over quite a few years I must have used routers from Stanley, Bosch (blue), Hitachi, Ryobi, Makita, Metabo, Elu, deWalt, Porter-Cable, Festool, etc and yet none of them have ever allowed me to just pop in a guide bush and for that guide bush to be absolutely concentric with the router collet. They always need to be centred, which is why many manufacturers and some tooling firms sell guide bush centring mandrels (sometimes called centring cones) such as this one.

I suspect that the accuracy comment is more to do with the fact that when using the Trend HINGE/JIG a longer bushing is preferable. What I don't understand is why the manufacturers invariably supply countersunk head screws which actually limit or curtail any adjustment.

 

[cjard]

Thanks JnK. I've taken to ensuring I always use the router the same way round to ensure that each hinge slot is at least consistently inaccurate and it seems to be working out better.

The other thing I finally figured out yesterday after routing 4 perfect slots, one that was a little bit deep and one that was nearly twice the depth it should be, why the depth was changing. Nothing was changing with regard to the router settings and the jig wasn't spontaneously getting thinner. Accumulated sawdust under the jig should have made things shallower so I was really puzzled until I noticed he bit was working it's way out of the collet. I've no idea why it happens, the nut was sufficiently tight and the bit was inserted to the proper depth. I suspect it has some slight rifling where the shank has been ground so it's effectively like a shallow screw, and if it had slipped/spin in the collet it would have been inclined to come out. Why it should slip I'm not sure, but maybe the first time it starts to work its way out the resistance en starts increasing if I'm plunging to full depth and it makes the situation worse. I've taken to checking before the start of each cut, as I think 3mm of oak isn't an unreasonable amount to remove in a slow single pass. If you think I should be removing less and doing two passes, let me know?

 

[Deleted member 174758]

.....so I was really puzzled until I noticed he bit was working it's way out of the collet. I've no idea why it happens, the nut was sufficiently tight and the bit was inserted to the proper depth

I'll answer a question with a few of my own:

1. What type of cutter is being used? (spiral or straight, 1-flute or 2-flutes, what diameter, what shank)

Spiral cutters are far more prone to pulling out, especially on routers with a single slot collet. Similarly larger diameter straight cutters may display this tendency, too. Single-flute cutters tend to vibrate more and that makes them more prone to slippage.

2. What diameter of shank is being used?

The larger the better

3. How old is the cutter? Is it a cheapo cutter or a better quality one?

Cheap cutters can go "off" (blunt) remarkably quickly in aggressive timbers such as oak. If your cutter isn't sharp that can cause issues.

4. Is the cutter correctly inserted? Has the collet ever been abused? Is the collet clean?

Whilst it can be tempting to try and get extra cut depth by pulling the cutter out of the collet it isn't the best of approaches.= because it can decrease grip. Similarly pushing the cutter so far into the collet that the body of the cutter contacts or almost contacts the collet/collet nut means that hen the collet is tightened (onto the radiused filet between the shank and the cutter body) it will be deformed, potentially permanently. Pull the cutter too far out (so that the full length of the collet isn't filled with cutter shank) the tighten-up and you can deform the top of the collet (again, permanently). If the router is put away without a cutter in the collet, is the collet ever tightened? This can deform a collet (again, permanently). The collet interior, cone inside the router shaft and tapered insides of the collet nut must all be kept spotlessly clean (Trend sell small brass brushes for just this purpose) and lubricated (light machine/sewing machine oil - not WD-40). Rusty cutter shanks are also a no-no and the same comments about cleanliness and lubrication apply. All these components get resin and all sorts of crap (resins, MDF dust, etc) on them which can affect performance

5. What speed are uou setting it to run at?

Just musing on the idea that 30,000 rpm is very fast and that a 12mm cutter (if that is what you are running) might be better run at 24,000 rpm especilly if there is no dust extraction

.....I think 3mm of oak isn't an unreasonable amount to remove in a slow single pass. If you think I should be removing less and doing two passes, let me know?

I think it's a reasonable amount, too, although in oak and with a smaller-capacity router I'd be tempted to do a couple of passes to get that depth of cut, depending on the cutter in use, router, etc. Also note that having your router attached to an effective vacuum cleaner not only makes your working environment better, but also makes life easier for both the router and cutter because the extra airflow keeps the router and cutter cooler, the extraction helps keep the cutter cleaner (and sharper) longer and also removing the waste when you make it means that there is less re-cutting of mterials so the cutter runs cooler, gets less blunt, etc.

These small "trim routers" have miniscule collets which makes them a lot more marginal for doing bigger cuts/using bigger cutters so they are far more sensitive to minor mistakes in usage, lack of cleanliness, etc. I've started to (re-)discover this as I use a Makita RT0700 more and more

 

[cjard]

It's a trend 2 flute half inch straight cutter with a 1/4 inch shank.. came with the routing starter set that was bundled with the router starter set.
Probably fair to say it's a cheap one, as the entire set is twice the price of a dedicated hinge cutter. The instructions said to insert the shank at least 3/4 the way, and it's only a short cutter so this is what I did to get a reasonable depth of cut. It's brand new, xmas present and has done about 5 oak doors and beech cases, 3 hinge slots per door.. it still looks OK and I've been reasonably careful to avoid burning the wood/overheating the cutter I think.. something of a routing newbie though. The cutter said max 28krpm, and I think I set the router on 3.5 which was about 24krpm..

As a side note on technique, I was told something that disagreed with what the manual said. The advice was "work anti clockwise", but this surely can't be a universal advice, because it depends which side of the cutter is doing the cutting.. the manual said to ensure the cutter is trying to push back against the movement of the router and this is what I've been doing. I was also finding the router would do a good job of chipping the face of the door if I moved so that the cutter emerged from the door face. I've taken to plunging a semicircle on whichever sideman of the hinge slot would suffer breakout, before running round in a circle. It seems to work, though I don't know if it's correct

 

[Deleted member 174758]

It's a trend 2 flute half inch straight cutter with a 1/4 inch shank.. came with the routing starter set that was bundled with the router starter set.

http://www.screwfix.com/p/trend-rou...et/85954#product_additional_details_container
Can't fault that, really. I'd suggest that you might just be better off taking your 3mm in 2 passes and see if that makes things any better - if nothing else it will reduce the load on the motor.

As a side note on technique, I was told something that disagreed with what the manual said. The advice was "work anti clockwise", but this surely can't be a universal advice, because it depends which side of the cutter is doing the cutting..

True enough. When cutting around the outside of a square or a circle (e.g. a table top or a circular picture frame) then the cut must be anti-clockwise - around the inside of that circular picture frame the cut should be clockwise. The "rule" is materials and cutter to the left, fence or bearing to the right. In both cases the router is pushed away from the body (I've seen "so-called" joiners pulling routers towards themselves enough times over the years to know that even folk who should know can get it wrong). It means that the cutter always tends to pull the bearing or fence inwards, towards the work and it is done to avoid the issues which can arise from "climb milling" (as would occur if the router were in the same set-up pulled towards the body) where the action of the cutter tends to push the bearing or fence away from the work (resulting in rough cuts and far less controllability - and possibly even resulting in operator injury if things get really out of hand). The main thing is not to make the cut so heavy that the motor starts bogging down (dust extraction helps here) and wherever possible to restrict the cut width to no more than 1/2 the diameter of the cutter or less (which reduces anty kickback tendency drastically)

The way I deal with hinge recesses is to rout the far end of the recess first - I cut inwards by just over 1/2 the diameter of the cutter and doing this reduces the tendency of the edge grain to break-out (although a spelch block - a piece of scrap clamped to the face of the door - is better at that) - then to rout from the nearest end towards the farthest end. I try to avoid plunging into the timber, instead dropping the cutter to the cutting depth outside of the material as this seems to reduce cutter wear.