Old Hitachi angle grinder help please

[ptrott]

My 25 (or more) year old 4" Hitachi angle grinder is coming up for retirement, and I wanted to know what power (Wattage) it is. Unfortunately all information on the plate, except the serial number which is stamped in, has long since rubbed off.
I tried a Power Meter on it, but the reading jumps all over the place, so no use.

Does someone have one of these old beasts that has the info still intact on the plate?

Cheers.
Phill.

[TermiMonster]

My 4" Hitachi, (which is not 25 years old, more like 10), Model G 10SD1, is 700watts.
HTH
TM

[BobL]

Phil,

The Power meter might work better and be more accurate when the grinder is under load. Either way it won't probably won't give a measurement that is the same as the original rating. Most 4" grinders are in the 650 - 750 Watt range.

[ptrott]

Thanks guys. I know the new ones are 650 to 1100, but I wanted to know what my old one is so I can use it as a reference point.
A mate has the identical same one, and the plate is in better nic than mine. He recons his looks like it reads 430 watts, which sounds by todays grinders to be horribly underpowered, which mine was certainly not.
If it was indeed 430 watts, then I would be happy with any new one, as far as power is concerned, because the lowest powered decent one I can find is 650 watts.

[Avery]

Be aware that watts aint necessarily watts.

Tools used to be rated by the power developed, now they are rated by the power consumed.

Old watts were bigger than new watts.

[jatt]

Recon those German watts are diffferent to the Chinese ones.

Just to add more confusion to the mix :D

Of course a lot of the brand name name stuff is now churned out of China along with the cheapies.

Makes it a bit harder to try n sort out the wheat from the chaff. I'm still buying the brand name stuff when it comes to hard worked and commonly used stuff. The gear is still goin, despite the flogging the're given, so I'm not complaining.

[Gerbilsquasher]

Can we have a photo? My old green machine is still going and it's about 20 years old, but doesn't get out as much as my 5" variable speed Metabo.

Hitachi makes good stuff, but I don't know if they have recently given in to the lure of cheap (read: exploited) Chinese labour....:(

[Gerbilsquasher]

Just had a look at mine, all the information is missing too. However I seem to recall something said about '650 watts'.

Hitachi did make one in a similar casing which was black and green, rated at 1100 watts. Hell of a handfull for a 4" grinder....:wink: You could actually justify using the side handle for this one!

[ptrott]

Hmmm I was wondering about the possibilities of the "Watt" being re-valued over the intervening years. Sounds like it might have happened.

Regarding the origin of manufacture, I was tossing up between Dewalt, or going Hitachi again. I got Dewalt 18V Lithuim drill & impact drivers earlier this year, and am very impressed with them, but get this, the battery charger is made in Thailand, the batteries are made in China, the drill & impact drivers are made in Mexico !!!!!
Who knows where Hitachi are made now. My original was made in Japan, but I bet the new ones are not.
Being from the "Old School" I tend to think that weight has something to do with quality, or is it just that I feel I am getting more for my buck if it is heavier? the Dewalt drill certainly has weight for your dollar. On this basis, I am looking at, in weight order:-

Hitachi G10 SD2 at 760 Watts, 100mm, 1.6Kg ($119) = 7.4c/g & 15.6c/watt
Dewalt D28113 at 900 Watts, 115mm, 1.7Kg ($129) = 7.6c/g & 14.3c/watt
Dewalt D28108-XE at 800 Watts, 100mm, 1.7Kg ($130) = 7.6c/g & 16.2c/watt
Dewalt DW803-XE at 800 Watts 100mm 1.8Kg ($109) = 6.0c/g & 13.6c/watt
Bosch GWS 7-100 at 720 Watts 100mm 1.8Kg ($92) = 5.1c/g & 12.8c/watt
Dewalt D28106-XE at 1200 Watts 100mm 2.0Kg ($112) = 5.6c/g & 9.3c/watt

This makes the last two the cheapest per kilo, and the last one, the Dewalt D28106-XE the chepest per watt by a long way.

Any comments on the Dewalt D28106-XE would be greatly appreciated :U

[Graziano]

My 1983 vintage Hitachi 5" grinder is rated at 1250 Watts. The tool shop guys say it looks like the body of a larger size grinder but geared for 10 000 rpm/80 m per sec that a 5" disc needs.

[ptrott]

My 1983 vintage Hitachi 5" grinder is rated at 1250 Watts. The tool shop guys say it looks like the body of a larger size grinder but geared for 10 000 rpm/80 m per sec that a 5" disc needs.

That adds to the mix. Some of the 4" are only 10,000 RPM, which from what you are saying is too slow. The D28106-XE is 11,000 though. :2tsup:

[TermiMonster]

The G10Sd1 is 11000/min (made in singepore).
TM

[Dingo Dog]

I have one of those in your vintage, genuine made in Japan stuff, still going strong, also have one of those rip ya bleedin arms off bigger models. Cant help you though, I am back at work on a remote mine site, wont be back in Perth until another 11 days.

DD

[malb]

I tried a Power Meter on it, but the reading jumps all over the place, so no use.


Motor power consumption and output are an instantaneous thing, highly dependant on the load applied, which is why the power meter readings change a lot over a short period of time.

The ratings applied by the manufacturers are primarily limited by the tools ability to disipate the heat generated in using the unit. A secondary limitation is the carrying capacity of the switch and speed control module if fitted.

When operating completely unloaded, the unit will only draw enough power to overcome the mechanical friction of the bearings and transmission and the electrical losses due to winding resistance within the machine. For an 800W rated unit this might be about 150 to 200 W. The power output at this point is effectively zero as no external work is being done by the unit.

Once the unit is set to work, (i.e. the wheel or disk is applied to some other material) the power draw will increase in proportion to the load being applied to the wheel /pad. Most of this additional power will be delivered to the job at hand, but the friction and winding losses will also increase as the the bearings, gears etc are transmitting additional power and will have higher losses. The user has contol over the applied pressure and feed rate, and hence the way the tool is loaded and its overall power consumption and output.

The tool rating becomes significant if the tool is worked heavily for a prolonged period, when the friction and winding losses increase the internal temperature of the unit. At some point the power losses will equal the inbuilt cooling potential of the fan system of the tool, and the temperature will rise above the safe rated temperature for the windings etc. Continuing to operate beyond manufacturers rated power for extended periods will result in the winding insulation failing and creating shorted turns in the windings which will destroy the unit.

One development over the past thirty or so years to cater for user desire for power is that the manufacturers have opted to use higher temperature limits, allowing for higher tool power ratings without actually redesigning motors or spending more to produce them. When I completed my Engineering course in the early 80's winding wire insulation was normally spec'd for 70 deg C, today the same materials are typically spec'd for 105 dec C, allowing a 50% increase in the power rating of a motor without any need to redesign it. However, there is very little reserve for abuse, whereas there used to be a substantial amount years ago.

[old_fella]

I got a 4 inch at work that is 1400 watt, its a makita but they are alot dearer think it was around 340 or something.

[ptrott]

Thanks gents, especially Malb. for the detailed explanation.

Looks like the the published specs are only a bit of a guide, so as much as my cents/gram figs were a little 'Tongue-in-cheek', they are as good as any:U

I will go and look at some of the mentioned brands & see if there are any 'Stand-out' ones among them.

Cheers.