Gha cutter grinder refurb/advice

[von dutchParticipant @vondutch]

Hi all hope you are well.I recently acquired a gha tool and cutter grinder for my workshop,it needs a clean up and de-rust but is mostly there.Im after some advice guidance?!it’s an earlier model so has the very rare 16mm shank x1.2 thread collets.Im considering making an er20 collet adapter to hopefully solve that problem unless people think it will hinder my ability to regrind cutters etc.Also came with an original 3 phase motor that is not dual voltage but does have 3 wires coming from the motor windings going to a block and then 3 out going to the power supply.My question is can this motor be rewired to run on low voltage ala vfd 230v?Any advice/input greatly appreciated.

[Andrew TinsleyParticipant @andrewtinsley63637]

You could probably alter the motor to give 240 V 3 phase (Star / delta change.)> You will have to dig into the windings to find the star point where 3 of the separate windings are connected.

If you are not au fait with 3 phase then get someone who is competent to change the windings to delta configuration. I have never found a motor where it is impossible to get at the star point, but other people have said there are some that it is impossible  locate the star point.

There are VFDs that have a 240 volt input and a 380 volt (or thereabouts) output, but they are not common and are more expensive.

It can depend on the state of the windings, if they are very old . then the insulation might not be up to a spiky VFD voltage. I did convert a 1930’s 3 phase motor to delta and ran it off a VFD. However I decided it wasn’t worth the risk The motor was an integral part of a high speed drill and would have cost a fair bit to have it rewound, if it died on me. As it had been reconfigured to 240 V 3 phase . I simply used a capacitor to create 2 phases and a phantom phase. This was OK because the drill didn’t vary its load overmuch on very small drills, so a suitable capacitor was fine in this application.

Andrew.

[von dutchParticipant @vondutch]

Hmmm fair point I wanted to keep it all

original and use the motor that came with it but I have seen new 3 phase motors dual voltage quite reasonable.In my electrical nativity I thought I could just change the wires over at the connector,trouble is it’s finding someone to look at the motor/assess what needs doing without charging over the top cost.Thanks for your input on the motor!:)

[DC31kParticipant @dc31k]

Andrew is being quite cautious in what he is saying.

You are better to show us a picture of the data plate on the motor than to show a connection box.

The ‘spiky’ VFD voltage issue is over-stated for something that will run at a constant speed and is very low horsepower.

This thread has some good pictures concerning converting from start to delta.

https://www.ukworkshop.co.uk/threads/star-point-in-three-phase-motor.113222/

If reading it fills you with dread, take another route; otherwise have a go. Wear wellies and only touch it with a stick the first time you power it up. A modern VFD has so many inbuilt anti hari-kari measures that you would have to work really hard to do something terminal.

You have to look at the collet set up – an ER collet will have a nut projecting from the spindle housing, whereas the standard collets have their face almost flush with the housing. Providing this does not reduce clearance or run out of adjustment somewhere, it would work.

The grinder is a direct copy of the Deckel one. A manual for the Deckel grinder is at neme-s.org.

[von dutchParticipant @vondutch]

[bernard towersParticipant @bernardtowers37738]

Good idea to make ER tool holder I made one for my Stent and have never looked back.

[von dutchParticipant @vondutch]

True about the collet nut,I’ve researched it to death getting hold of the original collets,think I found someone in Europe selling metric ones but only in limited sizes.Hence my thoughts to go with making an er adapter.I was considering using the motor as it’s good ol British stuff which normally seems to be made to last back then my meddings power saw is running on a vfd powering the original brook Compton motor(that is dual voltage)and runs really well.As an absolute last resort I’ll have to get a chop suey motor.

[Pete RimmerParticipant @peterimmer30576]

A lady on the mig welding forum has just done this very modification last week.:

**LINK**

[BazyleParticipant @bazyle]

The mig welders above seem to have done no research at all into how Deckel single lip grinders work!

Although the OP wants to ‘keep original’ the following video seems like a great upgrade and btw applies to a Quorn equally. Not sure who put me onto this video a few days ago – so whoever it was if this forum, thanks. Normally I would fast forward such a long exposition but after a few jumps I found it sufficiently good to watch real time, and I don’t even have one of this style.

Robrenz Deckel clone modifications. https://www.youtube.com/watch?v=ELTL9qTJg-o

[von dutchParticipant @vondutch]

Interesting link that thanks I will

be doing something similar my collets are 16mm dia shank,so was thinking of making an er20 collet sleeve.I could remove the collet holder and bore out the housing for bearings etc and that would give me more collet options but it will also permanently alter the machine is that a bad thing in my case maybe not?

[Bazyle]

On Bazyle Said:

The mig welders above seem to have done no research at all into how Deckel single lip grinders work!

Although the OP wants to ‘keep original’ the following video seems like a great upgrade and btw applies to a Quorn equally. Not sure who put me onto this video a few days ago – so whoever it was if this forum, thanks. Normally I would fast forward such a long exposition but after a few jumps I found it sufficiently good to watch real time, and I don’t even have one of this style.

Robrenz Deckel clone modifications. https://www.youtube.com/watch?v=ELTL9qTJg-o

I’m pretty sure that neither of the two protagonists have a Deckel or a clone thereof. I have an original one which I seldom use but when required it does a great job. Mostly it’s used for making custom ground carbide lathe tools.

You’re right about Robrenz he is one of the few nonsense-free open-faced contributors that cover their work and reasoning process thoroughly whilst remaining very engaging. He posts a lot on instagram and it’s usually very interesting even if it’s only marginally topical to the viewer.

[duncan webster 1Participant @duncanwebster1]

I once had a Ferret (I think) bench grinder which I converted to single phase using a capacitor as mentioned above. It was a more powerful motor, but it worked a treat. Finding the star point was easy. The motor manufacturers recommended not using vfd on an old motor. Can’t remember why. How to do the capacitor thing is detailed in the Workshop Practice motors book. It’s also a lot cheaper.

[Pete Rimmer]

On Pete Rimmer Said:

“I’m pretty sure that neither of the two protagonists have a Deckel or a clone thereof.”

The bright green workhead they showed, available is several sizes on ebay, is part of a range of far-eastern machines based on the Deckel. I think they use a proprietary collet just to be awkward but one of the modification routes is to bore out to 5C. If you think you want a Quorn but not the work one of these, a bench grinder, and a 25mm bar and you have a Colyer-Casey.

I like your description – sums it up:
nonsense-free open-faced contributors 

 

[noel shelleyParticipant @noelshelley55608]

If old 3Ph gear is your thing then a static or rotary converter( transwave Etc ) may be the way, saves looking for star point and may be ruining the motor. I know there not cheap BUT they are plug and play. I use one on a drill grinder ! Noel.

[duncan webster 1]

On duncan webster 1 Said:

I once had a Ferret (I think) bench grinder which I converted to single phase using a capacitor as mentioned above. It was a more powerful motor, but it worked a treat. Finding the star point was easy. The motor manufacturers recommended not using vfd on an old motor. Can’t remember why. How to do the capacitor thing is detailed in the Workshop Practice motors book. It’s also a lot cheaper.

 

My Deckel uses a capacitor for phase shift on it’s 3 phase motor (but it is dual voltage) and so does my Union tool grinder. They both start and run perfectly well, though slowly for the first time if it’s particularly cold. It works well for grinders with their low-load startup. I hid the capacitors inside the base so you would barely even know.

[von dutchParticipant @vondutch]

A few solutions there regarding the 3 phase for me to look into thanks people.I had seen those green generic chop suey “angle mounts with collet top slide” on eBay and again I did give that some thought to.Im also aware of the purchase price I paid for the cutter grinder I’m trying to keep it on a budget as to make it a worthwhile purchase,hence making a collet holder and hopefully utilising the original motor.later hope to make a lathe tool attachment and maybe an end mill attachment as well.I see Asian clones going for around a grand and 2nd hand deckel clones for not a great deal less.

[Howard LewisParticipant @howardlewis46836]

If you need to take 16 mm work, you will need ER25 collets.

ER20 only got to 13 mm.

At least all the sizes use a 1.5mm pitch thread for the Clamp nut. These are available, (I get mine from Arc Euro Trade, since do not feel clever enough to make them.  A friend did, and it was a splendid job).

If you get the collets first, wrappoing emery around one, will allow you to “grind the internal taper of the adaptor to matcvhn the collets.

BUT, BE CAREFUL. Don’t force things. They grab very easily, and snatch out of your hand.

How would I know that?

Howard

[Steve RParticipant @steverichardson2]

a manual for the 2GC is available online for free.

With the ER collet chuck you will lose workspace which is a little limited on these machines.

did you get any of the original collets?

[von dutchParticipant @vondutch]

I got one 1/4 “ collet,I can see the front of an er collet chuck will stick out a bit hindering clearance,however the top slide collet holder will move backwards about an 1” so thought that might compensate for it?I was also looking at the European supplier selling metric 16mm shank x1.2 pitch collets (there selling a few metric only sizes!)and looking at the possibility of boring them out or reaming/honing annealing if i have to can I use them after in soft state etc.

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