Quote:
Originally Posted by BrianAllen
I am in the process of replacing the base to a Bush PB.12 (eaten by woodworm) and need a router to rout the 6 channels for the aerial wires.
I will probably never use it again, so would like to know if anyone can recommend a "cheapie".
Thank you.
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I know this is a vintage radio forum - not a woodworking forum, so I was a bit hesitant about posting this diatribe, but given that for most of us, myself included, cabinetry is our weakest attribute, maybe these notes about the use of routers will be relevant enough to be thought acceptable.
You don't say what width or depth the channels need to be, how far apart they will be, or what material the base is Brian, but if I assume that maybe the width of each slot will be 3mm and perhaps 5mm deep, then a 'palm router' would be more than adequate for that task. If your bases is plywood, as I guess it might be, I've made some comments about that further down the page.
Most people will have firmly fixed in their minds that with power tools, 'you get what you pay for', and likewise with router bits. To an extent, that's true, but where routers are concerned, it's the manner of their use which often leads to failure, or even a burnt out motor. Routers are an acquired skill and the tendency for inexperienced users is that if they want a groove say 12mm deep and 6mm wide, they'll set the depth to 12mm and expect to rout the groove in one pass. They will also tend to use the router as they would say a circular saw and 'drive it' rather than to let the bit take its time. A 12mm depth slot with a 6mm diameter bit in softwood using a DIY router would take maybe 3 passes, or in hardwood, maybe four, especially with a hobby grade router bit.
Sometimes, when say cutting a bead on the edge of a piece of timber, inexperienced users will start with the router close to them, and push it forward as they would a circular saw or jigsaw. It seems to make sense. However, if that is along the left hand edge of a board, pushing the router forward is rather like setting a drill in reverse and expecting it to drill a hole. They need to start at the far end and bring the router towards them so that the cutting edge of the bit engages with the edge of the timber - not the trailing edge. (Along the right hand edge, of the board, the router would need to be pushed forwards).
The Palm router at the link below or something similar would I think meet your needs, sensibly priced at £29.99 with free P&P from a UK supplier.
The spec states:
This is NOT a Makita, however most of parts are compatible with Makita RT0700C
Chuck diameter: 1/4" / 3/8"
- No load speed: 13000 -33000RPM
- Input power: 710W
- Rated Voltage: 220 -240V
- Variable speed control dial: 6 speed
- Plunge Capacity (Trimmer): 0-40 mm
- Plunge Capacity (Plunge): 0-35mm
End quote.
http://vi.raptor.ebaydesc.com/ws/eBa...=1582705863423
It seems to have an adjustable side guide, so you wouldn't need to make a jig to guide it along the timber for each slot. It comes with a 1/4" collet, and a 3/8" collet for the chuck, and even a spare pair of brushes, not that you're ever likely to need them.
As to router bits, they normally have two cutters, but small diameter bits such as 3mm, will only have one as there's no space on the narrow shank to fit two cutters. That - together with the narrow shank - means that extra care needs to be taken it terms of allowing the tool to set it's own pace, and cutting a groove in several passes. For say a 5mm deep groove, a first pass of just 1mm, then two more passes at 2mm.
Below is a link to a cheap 3mm diameter router bit from Toolstation.
I've picked out some of the adverse reviews, which illustrate that the failure of the bits is more likely to have been through incorrect use, which could include not setting the router speed correctly. All routers have variable speeds - just as do lathes. There's a reason for that. The smaller diameter of the bit (or with a lathe, the diameter of the stock being turned), the less will be the speed at the tip of the bit. With each rev of a 5mm diameter bit, the cutting edge will cut 15mm of timber. However, with a 10mm diameter bit, it will cut 30mm of timber per rev. Thus, the smaller the diameter of the bit, the higher the speed should be set. In the case of the router I mentioned above, 33,000 RPM. Highest speed, with the router pushed at its own pace, as gently as the flap of a butterfly's wing. (Well, maybe a bit more than that!)
Here's an example of a 3mm diam bit from Toolstation (out of stock, but the pics miight be helpful):
https://www.toolstation.com/router-bit-straight/p67412
Here are some adverse reviews of the Toolstation bit, which - at least in part - I think illustrate the shortcomings of the user rather than the bits:
"Not robust enough for hardwood. Sadly this item broke after less than 1m of cut in my hardwood worktop".
Well yes, hardwood calls for special care, but the bit snapped with only 1mm depth when not being forced - Really?
"Not very strong, bust two. Ok for odd short jobs".
Again, I'm sceptical about whether the router was being correctly used, but at only £1.30 per bit, really, they're consumable items.
"These router bits are very cheap but they do break easily. I was routing out a groove a few mm's deep and a couple broke. You have to take it very slowly and don't push the wood hard against".
That says it all. A top quality Trend bit in the wrong hands will snap like a carrot.
Just a point about routing grooves close together in plywood:
Wood has a similar structure to a bunch of straws. When you cut a groove in a length of solid timber along the grain, the straws run the full length of the timber, so won't present any difficulties. However, if you cut grooves in plywood, every other ply will be cross-grained, so if say you cut grooves only 5mm apart, each ply between the grooves is in effect, a bunch of straws just 5mm long. They will have little structural integrity and unless great care is taken, will give up the ghost and tear out.
I've attached a rough sketch which I hope might make clearer what I'm saying.
The second pic is of a comb joint test in 6mm thick oak, with 6mm combs for a project box. If not done slowly with care, some grain would tear out.
Not to take the thread further off topic, I've attached a couple of pics of a slimline pen I recently turned and a box I made in which to house it. The half-round slots I cut into the American Ash & African blackwood base and lid for the pen box were cut in two passes even though quite shallow. One pass would have wrecked the box.
I hope these ramblings are of use and relevance.