Tenon machine thingy

[jfc]

Single end tenoner is it ? I've seen them and they look big and scarey but i think i may want one ;D Ebay throws up no hits so where do i look ?

[Stree]

No hits?

search.ebay.co.uk/tenoner

[Scrit]

Look for Multico TM, Sedgwick TESH, etc. as you will need three phase for most machines and those two made/make single-phase machines. A second-hand machine will probably cost more than your spindle (by quite a way)

Scrit

[jake]

I nearly bought a Sedgwick morticer a while back from an auction house, but they wanted to sell it as part of a job lot, with a spindle, a planer/thicknesser, and a dual head tenoner, for £1200. I didn't have the space to store it and they wanted it cleared within the week. Gah, still regret not hiring some storage. The bottom four on here www.centaurauctions.co.uk/tools_equipment.html

[Scrit]

I like the description, "twin head spindle moulder"

[jfc]

Could i not use an inverter to make a 3 phase use 240 power ?

[Guest]

jfc said:

Could i not use an inverter to make a 3 phase use 240 power ?

You can indeed , the electronix versions also allow you to control the speed of the various machines if needed.
They create an artificial third leg and allow the full power of the motor.

The very latest ones are digital and these generate the actual third leg and allow much bigger hp motors to be used and also they allow speed control etc.
Another plus of the digital versions is they use very little power compared to 3 phase.
I have two machines running at the moment using them and they work very well. The only 2 downsides are you need a much bigger hp inverter than the hp of the motor and that pushes up the price considerably. The other downside is some digital and electronic inverters put a small discharge down the earth of the power supply so you need to change the rcd rating to suit. I overcame this problem by using a split load to make the other power supplies ie wall sockets etc use the standard trip rating.

Hope this helps

[Scrit]

A few of points to note. Most tenoners have spindles directly driven at 3000 rpm (OK, 2850 rpm in reality) - run them any slower than 2000 rpm and they'll bog down in cut and potentially stall or in extreme instances kickback (as you are often asking them to take a heavy cut - unlike other machines tenoners have to take the complete cut in one pass) , run them much over 4500 rpm and you'll hit the problem of the blocks exceeding the speed for which they are balanced (not to mention potential bearing failure), therefore the ability to vary speed is pointless. In fact the ability to vary spindle speed is pretty much worthless on almost all static machines other than spindle moulders and pin routers.

I've used devices like the Transwave static inverter (the type which generates a third leg) and I found that the three legs are in fact far from equal; typically you'll see something like 360 volts, 320 volts and 200 volts on the three legs. This, I'm told, has implications for the long-term health of the motors (and can cause problems with low-voltage remote control gear if that is run off the "short" leg), but more importantly means that a 3 HP motor can become more like a 2-1/4HP one. For tenoning and chain mortising this can lead you into situations where the inverter overloads and trips or the machine stalls very readily.

Guest said:

Another plus of the digital versions is they use very little power compared to 3 phase

Actually, I think you're wrong there. A 3-phase 3HP motor will draw approximately the same current when running as a single-phase 3HP motor regardless of whether or not it is run via an inverter. When I ran my machines on inverter in an early workshop I got a saving of about 15% when the workshop was finally wired to 3-phase rather than running via a converter - this is the amount of power loss the inverter produces. I think the biggest differences between a single and three phase motors is that 3-phase motors draw less current at startup and (from experience) generate higher torque - one reason why 3-phase spindle moulders and pin routers seem to have more power than their single-phase equivalents.

Guest said:

The only 2 downsides are you need a much bigger hp inverter than the hp of the motor and that pushes up the price considerably.

Not only that, but with multi-motor machines like tenoners you need to observe a "power-up protocol" to ensure that you don't overload the inverter. Try switching both motors on simultaneously and the inverter will trip unless it is sized at something like 3 times the combined motor rating. Considering the average small (2 motor) tenoner runs 2 x 3HP motors (i.e. circa 4.5kW) the inverter may need to be able to supply 13.5kW at startup. Or just about the limit for a 60 Amp domestic consumer unit........ I used to run a workshop via an inverter and these were the sort of problems we had. They seem to be great for single motor machines up to 3 or 4HP, but above that they rapidly become extremely expensive to install. That's why I suggested looking at machines which were single-phase to start with - that and the fact that even "lightweight" 3-head industrial tenoners typically tend to have 8 to 10 HP motors (i.e. 6 to 7.5kW) and a physical weight starting at 600kg and upwards - the small Wadkin (the ECA) weighs in at nearly 1.25 tonnes as do many of the "smaller" British machines, such as those by Dominion, Wilson and Robinson (always assuming you have the £2k plus that even the tattiest example fetches).

By all means use inverters, but this is one application where the use is questionable, IMHO

For good measure this is what I mean by a small industrial tenoner:



Scrit

[guest]

Static Inverters Aaaahhhhhhhh I agree with you there been there done that.

Have to agree to disagree with regards to running costs with digital inverters against genuine 3 phase, my electric bill says very different ;D ;D.


I like your description of a small industrial tenoner ;D. I was thinking slightly smaller .

[Scrit]

I assure you that is a small industrial tenoner. the full-size ones look like this, as well you probably know:



What I was referring to before as a very lightweight machine suitable for a small shop (and a type available as single phase in any case) was the Multico, like this model TM:



or the Sedgwick like this TE:



The biggest issue and most serious issue in digital inverter technology is that of loss of torque on the motors, partly as a result of the "steps" in the output frequency of the inverter. On three phase motors driven by three phase digital inverters (the norm for CNC routers) the motors, nominally rated for 18 to 24,000 rpm (max. continuous), can theoretically be driven as low as 500 rpm, but in effect below 12,000 rpm the loss of torque makes the machines untenable unless much larger motors are fitted or a much reduced feed rate or smaller cut is taken. This has resulted in a move towards 15HP and even 20HP motors on the current generation of CNCs because even 10HP motors run at 18,000 to 24,000 rpm through digital inverters show marked signs of loss of torque over their rotary converter predecessors. Industrial pin routers of 20 or more years ago could work at a similar rate to 7 to 10HP CNC routers when running at 12 to 24,000 rpm through rotary inverters but with with motors in the 3 to 6HP range. In other words digital inverters cost you power unless you start with large enough motors in the first case - a fact most woodworking machinery engineers appear to agree upon.

As to your leccy bill, well the fact is that a given amount of power costs a given amount of money - regardless of whether or not it's three phase or not, as any electrician will tell you. If you are using less power I'd say it was more likely to be down to more efficient modern motors with soft starts over older heavy motors on non Star-Delta starters than anything else.

BTW, Timberman, I'd be grateful if you could log-in when responding rather than coming on as Guest, thanks

Scrit

[lynx]

Scrit, where was the photo of the EKA taken and is that machine still for sale?

[cnc paul]

Hey Scrit

That is a nicly restored Wadkin, Who did it ?


Paul

[Scrit]

The EKA was from Timber Team at Earl Shilton in Leicestershire. The firm was started by two ex-Wadkin employees a few years back and they do make a good job of rebuilds. All three of the tenoners are from their site

Scrit

[lynx]

They do a very nice job of cleaning them up. I viewed a different EKA Wednesday just gone, Pity this was a costumers and sadly not for sale.

[Scrit]

They dopn't just clean them up. They strip down the machine and blast off the chassis before repainting. All bearings, slides, etc. are checked and rep[laced/remachined/reshimmed as necessary. Electrics are similarly revised and updated. In all a very thorough job. Me biased? Yes, because I had a machine off them a few years back which was like new

Scrit