Bandsaw Throat Plate

[OldWood]

Steve Maskery's BS Video sent me off to check the throat plate on my new 2nd hand bandsaw - Multico BS140-04.

I don't know how the previous owner managed to cut anything true as the throat plate is totally knackered. I hope this isn't an indicator of other problems !!

Steve doesn't tell us how to make a new one - quite rightly as each manufacturer has a different configuration I'm sure.

My problem is that the current one on my machine is perspex - is this normal ? It's circular too and screwed down with a pair of large csk screws.

Steve just shows the plate dropping in - does this suggest that the screws aren't really necessary ?

Rob

 

[woodbloke]

I made mine from some stainless steel and it's held in place and at the right height with a few blobs of Blu-Tack - Rob

 

[big soft moose]

Steve Maskery's BS Video sent me off to check the throat plate on my new 2nd hand bandsaw - Multico BS140-04.

I don't know how the previous owner managed to cut anything true as the throat plate is totally knackered. I hope this isn't an indicator of other problems !!

Steve doesn't tell us how to make a new one - quite rightly as each manufacturer has a different configuration I'm sure.

My problem is that the current one on my machine is perspex - is this normal ? It's circular too and screwed down with a pair of large csk screws.

Steve just shows the plate dropping in - does this suggest that the screws aren't really necessary ?

Rob

mine just drops in - so long as its secure from the top i cant see any need to screw it down (and easier not to as you need to pop it out everytime you change the blade)

as to making a new one - its easy enough to cut a perspex circle on a lathe - just stick it to a mdf disc with double sided tape then use a parting tool to scribe it out

if you dont have a lathe a scrol saw is the second best bet (put it on a centre pin clamped to the table and turn it into the blade)

either way you can also use the scrollsaw to cut the slot for the blade

 

[OldWood]

Thanks guys

Woodbloke's answer of stainless steel raises the question as to why they aren't all make of metal - why are throat plates seemingly sacrificial?

Presumably BSM, I don't have to use perspex - don't have any and am not minded to going to buy some just for this when I've plenty of wood around - but is some sort of wood better than others ?

Thanks
Rob

 

[Steve Maskery]

I wouldn't use SS myself for a BS throat plate.

The reason that throat plates get worn is because the blade twists when cutting curves, especially tight curves. The blade guides above and below resist this twist, but they cannot defy it completely.

I've never had a BS with a round TP, but my Mate-Brian-Next-Door has one and that is permanently knackered and he replaces it regularly. But it's only a circle of 2mm MDF - backing board for picture frames - so he makes a batch at a time. It's a bit more difficult to cut the original kerf in a round TP as you can't just run it against the fence, but it just requires a bit more care, that's all.

Mine are a good fit, but they don't really need to be that snug. But the advantage of a replacement TP is that it supports fragile workpieces, such as veneered ply, right up to the blade, which a standard original TP does not. That's fine for straight cuts, but the moment you rotate the workpiece for something shaped the TP will get cut. That's why stainless steel is not a good choice in my opinion, it will just knacker the blade.

My 2p.

Cheers
Steve

 

[OldWood]

Thanks again guys. A bit wiser now. Sounds like mdf as the material - or am I better to look for something a bit more sturdy.

Now the question is what is the purpose of the throat plate? Is it to support the timber as it is being cut, or is it an additional guide for the blade ?

If it's the former then there is a degree of logic that says that a circular one without screws is preferable as it will rotate with the blade as it twists - or perhaps that's what the TP is meant to prevent !

I can see the problem, Steve, of cutting the kerf with the circular one. Presumably it is always preferable to to cut it with the blade itself and not somehow off-saw ?

Rob

 

[Steve Maskery]

The throat plate is to support the workpiece right up to the blade. This is particularly important if you are cutting small parts. A gaping hole in the table would allow the possibility of the workpiece, of a small offcut of it, dropping inside and getting caught in the lower bearings or in the throat itself, for example.

I think MDF is the perfect material for this. Cheap, easy to cut to the right shape and perfectly disposable.

S

Edit - Pete's right, my TPs are ply, not MDF!

 

[woodbloke]

Steve - I used a lump of ss 'cos it was almost the right thickness and just needed a little shimming with some Blu-Tack to get it spot on. I agree about cutting curves...but I cut them very rarely so I'm not too bothered about that issue - Rob

 

[OPJ]

I hate round throat plates - it's always a bugger to cut new ones, even in batches! :x I reckon the safest way has got to be with a jig for your disc sander. I guess you could also do something on a lathe, sticking several together with double-sided tape... But then, you might still have the problem of thickness. There is probably a better solution but I ended up rebating the edges on mine so it sat slightly proud of the table (then, I planed it flush)... It's not the kind of router table operation I'd recommend - even with the disc stuck to a scrap length of hardwood... :?

 

[big soft moose]

Thanks guys

Woodbloke's answer of stainless steel raises the question as to why they aren't all make of metal - why are throat plates seemingly sacrificial?

Presumably BSM, I don't have to use perspex - don't have any and am not minded to going to buy some just for this when I've plenty of wood around - but is some sort of wood better than others ?

Thanks
Rob

i don't see any particular need for it to be perspex in steve's video it looks like his throat plate is made from plywood.

at the end of the day anything that is smooth, flat, the right thickness, and relatively rigid, but wont damage the blade if it comes into contact with it ought to do the job

 

[woodbloke]

Thinking about it a little more, the ss plate is a bit chancy so I might take it out and use it as a template to make another one from some thin mdf or similar...won't look so pretty though - Rob

 

[big soft moose]

I hate round throat plates - it's always a bugger to cut new ones, even in batches! :x I reckon the safest way has got to be with a jig for your disc sander. I guess you could also do something on a lathe, sticking several together with double-sided tape... But then, you might still have the problem of thickness. There is probably a better solution but I ended up rebating the edges on mine so it sat slightly proud of the table (then, I planed it flush)... It's not the kind of router table operation I'd recommend - even with the disc stuck to a scrap length of hardwood... :?

you can do them 1 at a time on the lathe and it only takes a few minuites per disc - i made myself ten spares in less than an hour in that way

1) mdf disc is mounted on the face plate with doublesided carpet tape arround the edge put not in the middle

2) stick the square of perspex or whatever to the carpet tape with light presure only

3) scribe out the disc with a parting tool (I made a little false tool rest with a grove in it to take the parting tool to get the right diameter "first time every time" like steve says)

4) the cut disc is in the middle where there is no carpet tape so it just pops out

5) peel off the waste from the carpet tape , replace with another square and repeat from step 2

in my experience the tape stays sticky enough to hold about ten squares before it looses adhesion.

next time you can just stick more carpet tape on top of the first layer and so on - simples

having cut the discs all that remains is to put the blade slots in them - for which i used my scroll saw , but a bandsaw with a fine blade would do it just as well.


as to the thickness - i find that 3mm perpex is exactly the right thickness - and one sheet will make va hell of a lot of plates before i need another one

 

[CHJ]

I turn mine up out of old Kitchen Chopping Boards (stepped diameter to suit recess) I turn them a couple of thou. oversize so that they are a compressed fit. Any pinching of the blade by the compressed slot is cleared upon first switchon.

 

[OldWood]

Just to add to my confusion as to what the throat plate is for, I was looking at my mate's Axminster an hour or so ago and it has a throat plate that seems to defy all that is said here.

It's plastic - OK that's not unreasonable, but cheap - and round, which is a cheap option also as it is just one round machine operation in the table casting - but it has a blade cut out which is 9mm wide, so no support there if you are cutting something small. Furthermore the edge of the disc is beveled so that the sharp edge of the table is there to catch anything going passed the blade.

I guess he will be looking to make a proper TP too.

Thanks BSM for your manufacturing procedure. But one question - I take it from Steve's accurate setting up of the TP for cutting the blade slot on his DVD, that he is of the opinion that it is important to cut the slot accurate to the machine. If you cut the slot as you are doing, aren't you assuming that the blade is running absolutely dead centre to the TP ?

By the way is there any guidance as to whether the slot should face the on coming work, or face away from it?

Rob

 

[Green]

I have mine facing the oncoming work and quite wide as I use it alot for marking the centre of square stock for turning spindles.
I rip a lot of rough sawn wood so my clearance doesn't need to be that tight.

Maybe make a few for different tasks?

 

[big soft moose]

Thanks BSM for your manufacturing procedure. But one question - I take it from Steve's accurate setting up of the TP for cutting the blade slot on his DVD, that he is of the opinion that it is important to cut the slot accurate to the machine. If you cut the slot as you are doing, aren't you assuming that the blade is running absolutely dead centre to the TP ?

By the way is there any guidance as to whether the slot should face the on coming work, or face away from it?

Rob

with regard to the blade slot cutting , I just used my original one as a template to mark the position and then cut the new ones to match, okay i'm assuming that the original one was accurate but it seems to work for me

as to which way the slot faces I don't think it matters that much, mine is behind the blade because when i take it off that way the disc slides to the front of the machine which suits my 'shop set up - if it was the otherway round it would slide to the back which would risk dropping it into an inaccesible gap between cabinets.

also if its behind the blade the work piece cant catch on it before the cut and after the cut the kerf is over the slot.

 

[Digit]

Another reason for the plate Rob is when tilting the table, the trunion is normally off set to the left, so without the plate, or a wide slot, the blade would carve bits out of the table. Exactly as on a TS.

Roy.

 

[OldWood]

Thanks for that point, Roy - I'd forgotten about table tilting. That's probably why the Axminster slot is so wide as a base level plate.

So I have learnt that the plate does *not* guide or stiffen the blade and is there to support any small work pieces past the blade.

The need for the removable plate then really comes out of the requirement to make the table tilt - with a wide slot then this can be achieved without changing the plate; trying to cut small pieces on a tilted table would then require a suitable cut plate.

I really don't know why I have laboured this discussion so much as I'm familiar with the equivalent plate on a TS - and this is just the same !! Doh !!

So I can now go with BSM's "TP Making Process" when I need it as I can't see myself making veneers or the likes in the near future; and, although looking a bit untidy, the perspex plate I have now seems good enough for average cutting.

Hurray !! and thanks to all.

Rob