JET BANDSAW JWBS-18

[Anonymous]

I have recently purchased a Jet Bandsaw JWBS-18. The blade has been renewed as the one it is supplied with is not recommended. I find the machine is underpowered despite its 2Hp motor and the speed a little on the slow side. General performance is no comparision with my 8 year old Electra Beckam 315 which is excellent - the Dure Edge blade makes all the difference ! I am considering a Newton-Teslar 3 phase motor. Most USA reports concern upgrading the motor. Are there any UK users out there please ? I would be interested in your findings and comments on the JET JWBS-18. Many thanks = Alan.

 

[Alf]

Welcome to the forum, Alan.

Well I don't have the 18", but I do have the 16" re-badged Axminster one. Although it has a smaller motor than the 18" I can't honestly say I've found it under-powered. I agree it pays to scrap the blade provided and get Dure-Edge blades, same applies to any bandsaw. In my opinion, if you use the right blade for the job, and it's sharp, then you shouldn't honestly need a lot of grunt in the motor. It's not like you're having to whirl round a large disk and cut a 3 or 4mm kerf like you do on a tablesaw. I s'pose this is a classic case of YMMV... I like mine anyhow - sorry you're not so happy.

Cheers, Alf

 

[Newbie_Neil]

Hi Alan

Welcome to the forum.

I don't have a Jet bandsaw, but as far as I'm aware all of the Jet kit is rated by output so it will appear to be less powerful than other machines.

IIRC they rate them at 100% output.

Cheers
Neil

 

[Mdotflorida]

Welcome Alan.

I have the Jet 18" bandsaw and have to say I have yet to be disappointed in anything I have asked of it.

Unlike yourself, it is the first bandsaw I have owned so I have nothing to compare it to.

As Neil has pointed out, Jet seem to rate their machines slightly differently to other manufacturers and I was a little dubious about their power ratings before I bought their kit. I have a lot of Jet kit and am more than happy with all of it.

Merry Xmas

Jeff

 

[Anonymous]

Hello All,

Many thanks to Jeff, Neil, and Alf who replied. All your comments noted and appreciated, Thank you. I agree with your comments Alf especially about having the right blade, and I find that the 5/8 3tpi Dure Edge blade on the Electra Beckham 315 does everthing I ask of it (Which is mainly ripping) It's a different story on the Jet JWBS-18 with an Axminster blade - its just not sharp so I'll be changing it out for a Dure Edge very soon.

Reference the power rating by output which Neil kindly explained is interesting and something I was not aware of so thanks for that. I have measured the input on the JWBS-18 and it takes just under 3 amps when the blade is running off load. An approximate calculation says 3amps X 240v = 720 watts which is along way from 1492 watts (or 2Hp that Jet are quoting !) Bear in mind the Output would be even less. (Purist please ignore I'm making using a DC calulation on an AC component but I did say 'approximate' and I don't think you'll find its that far out !)

Thanks for your comments Alf and I'm glad your happy with your Axminster Bandsaw. I'm sure I'll be very please with this one once I get a 3 phase motor on it ! (Newton Telsar if its not too expensive !)

A Very Merry Christmas and Happy New Year to you All.

Thank you once again for your kind interest.

Alan.

 

[Adam]

input on the JWBS-18 and it takes just under 3 amps when the blade is running off load. An approximate calculation says 3amps X 240v = 720 watts which is along way from 1492 watts (or 2Hp that Jet are quoting !)

Welcome to the forum. Have you measured it under load? I have to admit, you are the first person I have heard to consider any of the Jet range underpowered. It does sound like you have something with which to make a good comparison. Given I have the worlds most rubbish bandsaw everything seems better to me!! :?

Adam

 

[Newbie_Neil]

Hi Alan

Firstly, in terms of the blade, as you know Dure Edge are the best.

I'd send a pm or email to Jetman aka Nick at Jet explaining your problem.

I just cannot believe that you will need a three-phase motor and if your calculations are anywhere near accurate, then there must be a problem with the machine.

Cheers
Neil

 

[Anonymous]

Hi Adam

Thank you for your comments which are appreciated.

No I have not measured the current on load (but I should have done and I will) Some of our USA friends have found the machine underpowered also - but after fitting a new motor and link belt, they claim it is a whole new machine. Don't misunderstand me as the basic machine is very good and the first bandsaw I have owned that has a completely flat table !
The band saw handbook by Mark Duginske is excellent and has been very valuable in getting the best from my bandsaws.

A Happy Christmas to you

Alan.

 

[Taffy Turner]

Hello All,

I have measured the input on the JWBS-18 and it takes just under 3 amps when the blade is running off load. An approximate calculation says 3amps X 240v = 720 watts which is along way from 1492 watts (or 2Hp that Jet are quoting !) Alan.

The no-load current is not related to the power of the motor. The motor will only draw the current that it needs to maintain it's rated speed. When the saw is not cutting, the motor only has to overcome the friction etc required to drive the blade. When you start to cut, the load on the blade will increase. which will cause the motor to slow down. The motor will draw more current so that it can maintain it's rated speed, up to it's maximum rated current.

If the motor is a 2 HP one, and is rated on output, not input, then 2Hp = 1500W approximately. Most standard electric motors have an efficiency of around 85%, so input power is 1500/0.85 = 1765W. On a 240 V supply this equates to 1765/240 = 7.4A.

If you are able to measure the current when the saw is on full load, this is the value that you should see (approximately - there are other factors such as power factor which I have ignored for the sake of simplicity).

If you do decide that the saw is underpowered, I would seriously consider uprating the motor to a larger single phase one to avoid all the hassles of three phase. It may be possible to obtain a higher rated motor in the same frame size, or even get the existing one rewound to a higher rating.

 

[Newbie_Neil]

Hi Taffy

Thank you for the wonderful explanation.

The only point I can comment on is that the Jet figures, iirc, already take account of the efficiency of the motor so that 2Kw will be the real output.

Cheers
Neil

 

[Taffy Turner]

Neil,

Yes - but in order to get 2 HP out, you need to put in more, hence dividing by the efficiency.

FWIW it is possible to buy high-efficiency motors, which can go as high as 95%, but they are very expensive, and the cost is only really justified for process industries where the motors are running24-7. Although having said that, it can be a way of squeezing a few more Watts out if you don't have room for a bigger motor.

Regards

Gary

(I am not an expert on electric motors - I am sure Tony will be along soon with his far more expert views).

(Edited for typo's - Doh!)

 

[Vormulac]

Adam, as you seem less than impressed with your bandsaw,and presumably would not recommend it to anyone, what is it?

Cheers,

V.

 

[Adam]

Blimey, its a really really old three wheel bandsaw - one of these:

https://www.ukworkshop.co.uk/forums/viewtopic.php?t=2156

I got it for £15 at a boot sale. I don't normally buy stuff from car boots - but this was in a state, snapped blade, knackered belt, clearly hadn't been used for a long time based on the erosion on the table, and I needed one.

I have however put a Dure-Edge blade on, and although terribly slow, it did make it through some 2 inch Ash last night - which isn't bad all things considered. It's out-of-sync with all my other tools though - the only remaining major item I really should purchase is a good bandsaw - but I truly am out of space! In the meantime, it being bench mounted is a big plus, It doesn't take any floor space - and I can lift it onto my workbench when I need it.

It's faults though, are too long to mention, underpowered, impossible to get square table, difficult to tension, terrible dust extraction... however, I rarely resaw at the moment, so don't need the depth very often, and it works. These are standard issue in schools countrywide, so they must take a reasonably high level of abuse!

Adam

 

[Alf]

I truly am out of space!

You heard it here first, folks!

Cheers, Alf

 

[Newbie_Neil]

Hi Gary

Yes - but in order to get 2 HP out, you need to put in more, hence dividing by the efficiency.

Sorry to labour the point, but IIRC the 2Kw output quoted by Jet will be after dividing by the efficiency.

Cheers
Neil

 

[Taffy Turner]

Neil,

You are perfectly correct. If the 2kW (HP?) is the output rating of the motor, then that is what you get out of the motor under full load.

However, as efficiency = power out / power in

then power in = power out / efficiency

which gives power in = 2000 / 0.85
= 2353 W

It is the input power figure which you require to calculate the full load current.

The confusion is because most motors are rated on input power, not output power. Hence in most applications, the actual useable power available from the motor is approximately 10 - 15% less than the rated power, which always strikes me as being a bit of a con. In fairness to Jet, they don't do this, and rate the motor on available power at the output shaft, which is a more honest way of doing things.

If anyone is wondering where the other 15% goes, then most of it is converted into heat in the motor windings, hence the need for cooling the motor. For information purposes, variable frequency inverter drives are less efficient again, as you get losses in the motor, plus losses in the inverter, which is why the back of the inverter is a good pace to warm your hands on a cold morning!

Regards

Gary

 

[Newbie_Neil]

Hi Gary

OK, OK, I give up. As you quickly discovered I don't know my Kw from my HP. Oh, I thought that was Hewlett Packard. :roll:

Have a really good Christmas.

Cheers
Neil

PS I'll collect my coat on the way out. :wink:

 

[Nick.]

*bump this thread back*

Hello all,

Apologies, I know I'm about 3 months late replying - what was that saying about 'better late than never' ?? - Neil sorry too, you did pm me ref. this

Firstly, Alan, please call us on our office number if you are still having power problems - 0845 604 0064 - as the bandsaw you have should be adequately powered.

Jet are changing the power ratings in their next European catalogue to move more into line with everyone else re. quoting input - I still think everyone should quote output @ S1 - 100% as this is the purest way of telling how much power a motor actually gives out. The explanations everyone has already posted are all spot on re. the difference in input/output.
For the record, Jet in Switzerland have confirmed to us the power rating on each machine

(The most commonly quoted figure by most manufacturers is Input S6-40%)

The JWBS18 bandsaw is;

Input (S6-40%) : 2,588W or 3.53 Hp
Input (S1-100%) : 1,912W or 2.6Hp
Output (S6-40%) : 2,015W or 2.74Hp
Output (S1-100%) : 1,471W or 2Hp

Gary wins the prize for being the nearest to work out the input - I'm impressed :lol:

Best regards,

Nick - Jet

 

[Anonymous]

Hello Nick

Thank you for the input and output figures for the JWBS 18.

I have not solved the problem yet - however I am considering a motor change. Research has been on-going since November when the machine was delivered.

Thank you to everyone who replied with their helpful comments.

Kind regards

Alan