Gear head vs variable speed lathe

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Gear head vs variable speed lathe

This topic has 18 replies, 11 voices, and was last updated 13 August 2023 at 19:08 by Ady1.

Viewing 19 posts - 1 through 19 (of 19 total)

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11 August 2023 at 14:36 #14872
Chris12
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@chris12
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11 August 2023 at 14:36 #656098
Chris12
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@chris12
I'm looking at buying a first lathe, and was wondering what would be the pros/cons of a gear head vs variable speed lathe. From what I read :

Gear head :

– more power at lower speed

– less electrical issues

– less forgiving in case of user mistake

VFD :

– possibility to change the speed on the spot, no need to stop the machine

– more electrical components, not very reliable in some cases

– Quieter than gear head

I'm basically looking at the Warco WM250V and GH600. The GH600 isnt much more expensive and seems better built. Also I like the fact that there is less electrical components, which seem to be the weak point of import lathes.

However, being a first lathe, some user mistakes are to be expected, and it seems that damages on a gear lathe can be way bigger than on a variable drive.

Any thoughts ?

Thanks,

Chris
11 August 2023 at 14:52 #656099
Mike Hurley
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@mikehurley60381
Hi Chris. Your understanding of the pros & cons of the two types are totally correct. Unfortunately there is no simple answer.

Geared heads are inherently a bit noisier because they use straight cut gears, but give you the correct power (in respect of torque) in the ranges offered.

VFD gives infinite speed change and is much quieter, but can result in lower torque avaiable at lower speeds which can be a problem if working on larger pieces.

Ask 100 people and you will probably get a 50/50 split on which they think is best! – sorry.

My old lathe only had a geared head until I upgraded with a VFD a few years back. Now I have the best of both worlds (its still noisy though).

Horses for courses as they say

regards

Mike
11 August 2023 at 14:52 #656100
Ady1
Participant
@ady1
Just fixed the backgear pin on one of my Drummond Ms, the one from 1945

Great for drilling larger holes at slow speed

Backgear turns a hobby machine into a semi-industrial machine, electrical backgear systems have no hope of competing
11 August 2023 at 14:57 #656101
Thor 🇳🇴
Participant
@thor
Hi Chris,

The GH600 has a larger swing than the WM250 so you could turn a slightly larger pulley on the GH600 if that is important to you. The GH600 has a slightly larger range of pitches for screw-cutting and is heavier so if you can live with a bit more noise and get it into your workshop – go for it.

Thor
11 August 2023 at 15:15 #656104
JasonB
Moderator
@jasonb
What sort of things are you expecting to machine? The loss of grunt at low speeds really only comes into play when you have to run a bit slower to keep the cutting speed reasonable on larger diameter work.

The average model engine be that loco (wheels) traction engine (gears & Flywheel) and stationary engine (Flywheel) don't have that many large diameter parts when compared to the multitude of smaller items so it is possible to live with the loss on the odd occasion when it may actually be noticed. Carbide can go a long way to reducing the need to run slowly as the spindle can be run at about 3 times the speed that HSS can

I had a good quality geared head Emco before I got my Warco 280 and would go with teh Warco's variable speed which has been fine in over 10 years with a lot of use.
11 August 2023 at 15:20 #656105
Tony Pratt 1
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@tonypratt1
When replacing my Myford super 7 I lusted after old British iron, namely Harrison, Colchester, larger Myford, newer Boxfords, Austrian Maximat super 11, etc etc, but ended up with a Warco 290V. Once I got rid of the awful change wheel set up and replaced it with an electronic lead screw for my size of work it is hard to beat, I use carbide tips most of the time so run quite fast, the geared head lathes are noisy at the top end. Oh I have also fitted a clutch so I do not need to keep switching the motor on and off.

You will get many answers none of them right or wrong.

Tony
11 August 2023 at 15:42 #656107
Howard Lewis
Participant
@howardlewis46836
My tendency would be towards the GH600.

Ity might be a bity less versatile in terms of speeds, but is less complicated in electrical terms.

But, am a bit hypocritical in saying that, since my predessor to the GH600'is belt driven equivalent; but fitted with VFD, so the best of both worlds?

Instead of the original 12 speeds, I now have six, but each one has the speed range provided by the VFD.

Having said that a lot of the work, being bone idle, is done in mid gear (belt ) and with the VFD at max.

Has the VFD been unreliable? NO and it is coming up to 20 years next month.

The "jog" facility is invaluable when screwcutting, or using Taps or Dies. Back Gear and minimum speed or jog are very useful then.

Howard
11 August 2023 at 19:28 #656141
old mart
Participant
@oldmart
Having the motor speed control with a VFD complements the original series of belt speeds, or gear ratios and should not be an excuse not bother to use the mechanical gearing. When I bought a VFD and a new motor for the Tom Senior mill, the benifits of the original 4 belt speeds were not forgotten and the motor chosen was a 6 pole 1hp one. This runs about 900rpm at 50Hz so the Schneider VFD was programmed from 25 to 75 Hz which retains a good proportion of the power even at the lower speed provided the mechanical speeds are also used. Some people will try and get a motor to run at ridiculowsly low frequencies where the torque is very limited rather than bother to gear down.
11 August 2023 at 19:55 #656147
Ady1
Participant
@ady1
If you're a total newbie don't use the backgear for the first couple of months

Use the direct drive with a slack belt which will slip in the case of any disaster

Not just the lathe which will be safer, you will be too.

You'll know instinctively when you're ready to start using full power and start getting more serious

It's not very different to your first car or motorbike, go easy to start with, they can bite
11 August 2023 at 20:20 #656151
Chris12
Participant
@chris12
Thanks for your inputs, much appreciated.

Im planning to do steam engines, so no big diameters expected. My main concern with the variable drive is the electrics, which many people have been complaining over the years. Things may have changed though.

Also, a gear head being "all mechanics", i am more comfortable to repair/replace things. Which Im not with PCBs…

Out of curiosity : have any of you hit the chuck with the tool ? If so, what was the end result ?
11 August 2023 at 20:23 #656152
JasonB
Moderator
@jasonb
The inverter drive of the WM250's AC motor should not have the issues that some people may have had with DC brushed or brushless motors and their control boards found on your typical "Mini-lathe"
11 August 2023 at 20:40 #656155
HOWARDT
Participant
@howardt
Have a Sieg SC3, been in use for about seven years, despite some larger diameter cutting resulting n stalls and blowing the main fuse once and a few new drive belts all has been good, relatively. Now have a GH600 sitting on its pallet waiting for the arrival of an engine lift before being put to use. Will retain the Sieg for small diameter work for the time being, it is ideal for upto 25mm diameter but struggles a bit on thing larger in steel, although I have cut upto it’s 175mm limit all be it slowly. Choice is really on how quick you want to remove metal and level of competence. As a life long engineer I would have no problems with most manual machines, but space is the main prevailing factor in my workshop.
11 August 2023 at 20:48 #656160
Mick B1
Participant
@mickb1
The weaker torque at low speeds in the fast range on the WM250V has saved me a few broken tools that the Myford Speed 10 I used to have would've cheerfully crunched. The Warco just stalled, I retracted the tool, and carefully carried on.

In about 8 1/2 years, I've had no electric or electronic problems of any description.
11 August 2023 at 20:54 #656163
Samsaranda
Participant
@samsaranda
I have a geared head lathe, a Warco BV20, had it about 14 years now, went for a geared head lathe because I didn’t trust the electrics that were being used at that time, things are much better now. It has served me well and survived a few mishaps along the way, the only problem I have had was a replacement for the NVR switch. Although it is noisy I would still go for a geared head lathe, I just turn the radio up and it doesn’t worry me. Dave W
13 August 2023 at 18:12 #656406
Chris12
Participant
@chris12
Out of curiosity, what would be the max depth of cut on steel with the WM250v vs GH600 (or equivalent gear head lathe). Is a gear head really better at removal a lot of material quickly ?
13 August 2023 at 18:20 #656407
JasonB
Moderator
@jasonb
really depends on the diameter of the steel, this is my slightly larger 280 with the weaker DC motor taking 1/4" DOC = 1/2" off diameter from a piece of 1" steel

On the other hand when machining say a 10" cast iron flywheel 25-30 thou would be what I would be using

Edited By JasonB on 13/08/2023 18:45:57
13 August 2023 at 18:54 #656410
Chris12
Participant
@chris12
Thanks Jason. So powerful enough to remove efficiently a lot of material if required
13 August 2023 at 19:08 #656412
Ady1
Participant
@ady1
The big difference is if you work it hard or have a really tough job

Backgear can do it all day and your motor is hot as heck when you finish

and It can do it again tomorrow, and the day after…

It's just more reliable and you can fix it if it breaks, even I could get the small cog on mine fixed eventually

VFD stuff is great, only an eejit couldn't see that, but if you work it too hard things will happen that you can't fix

This is my Drummond on backgear stripping 8 inches of rebar in a single pass, I simply put it on a slow feed and it gouged out about 10mm with a knife cut

Edited By Ady1 on 13/08/2023 19:25:06
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