- Joined
- Mar 23, 2021
- Messages
- 357
Part One, VFD Conversion:
As some of you may remember I had a 1340GT on order for many months and ended up finding a deal on a used 1440GT just before my 1340 was to be delivered. The thread with that story is here: https://www.hobby-machinist.com/threads/my-1340gt-story.95922/
Since getting the 1440GT into my shop I have been busy with many projects getting the lathe upgraded and adding useful additions to it. When I acquired the lathe it was equipped with the single phase 2HP motor option, and I initially thought I would leave it that way for a period and learn to use the lathe before upgrading to a VFD with 3 phase motor. But it turned out that the motor in this machine was having issues and in communications with Mark Jacobs I decided to go ahead with the conversion sooner rather than later.
So now I am at the point where the conversion created by Mark is completed and installed. I have also added a solid tool post, tool trays, tool rack, spindle spider, mist coolant system and tailstock DRO. Of course the major addition was the VFD conversion and I would like to thank Mark for all his efforts and coaching along the way. I had Mark prepare a full conversion for my 3 phase 1340GT order long before it even shipped. I ended up selling that conversion with my 1340 to a friend, so this is the second one that Mark has built for me. His attention to detail and attentiveness to the process (helping us ignorant ones) made the whole process quite easy.
I'll begin with the VFD conversion. Mark found a deal on a 3 phase Marathon Black Max motor that he figured would be able to fit in the machine, not with much room to spare but fit none the less. I was a bit apprehensive ordering a motor this large and made many measurements as best I could going from pictures on an eBay listing. But Mark was dead on with his estimations and the motor ended up fitting in the machine with no other modifications than cutting off the encoder shaft that came on the motor and a few cooling fins. Here's a shot of the stock 2HP single phase next to the motor that Mark found:
In that photo you can see the encoder shaft sticking out the left side of the motor before I cut it off. The black conical piece in the background is the cover for the encoder shaft that comes on the motor. You can also see that I had to cut off a few of the cooling fins on the top of the motor in order to clear the backsplash.
Here's a closer look at why the fins needed to be cut off. I needed to ensure that I had room to raise and lower the motor for belt tensioning purposes:
The method of mounting the motor was one that Mark had sent me ideas for from other similar installs. I modified the belt tensioning system from what others have done in an attempt to make tensioning easier. Here's a shot of one half of my motor mount adjuster system:
Rather simple with a matching fixture at the other end and screw mechanism in between. Here's the jack screw being machined on the mill:
The motor mount is just two plates of steel cut to the appropriate sizes and a hinge made from steel tubing welded to the edges. I'm not going to show you any closeups of my welding as I'm just a hack at welding but can make two parts stick together well enough
I'll include a few shots of trial fitting the motor before I measured for and ordered belts:
Here was the motor when I first got in installed permanently with the new pulley and belts:
You can see that the two mounting plates are joined buy a rod, and that rod has spring clips at each end. With the original motor design there is no way to adjust belt tension or remove the motor (that I could see) without removing the backsplash. With this design I can easily adjust belt tension with the motor running (should I desire) and also remove the motor without messing with the backsplash.
This motors size of course required some modifications to the gear drive cover on the end of the headstock. You can see here that I cut the cover to make clearance:
It's cold and wet now here up north, so I have not painted anything as I don't have a place in my shop to spray. So I will have to wait until summer to paint whatever I decide needs it.
That's pretty much the details of the motor upgrade. For those interested the motor is a Marathon Y541A. It's a variation of the Y541 in that it is shorter, which in this case was necessary in order to not have to cut the backsplash. Here's a diagram that Mark found with this motors dimensions (if it doesn't show up here, look at the end of this post for a link). I won't go into the details of what is special about this motor as Mark is far more versed on that should anyone have questions as to why this motor was chosen.
The next order of business was where to put the VFD, braking resistor and main power switch. For the 1340GT build that Mark made for me I had put that and more in an enclosure that I was going to mount on the left side of the headstock pedestal. With the 1440GT Mark informed me that we could get all the needed components to fit within the main electrical compartment and inside the pedestal, negating the need for an enclosure. I liked this idea as it not only saves money (no enclosure to buy) but also saves me precious space in my small shop.
I came up with the idea of mounting the VFD on a standoff within the pedestal that would allow easy access/removal of the VFD. So here's what I came up with:
Just two pieces of channel mounted to a plate that mounts to the back wall of the pedestal. And on those are two socket head screws to hang a plate on with keyholes. This is all made with scrap aluminum I had from a project years ago. The idea is to move the VFD off the back wall, but just enough to not interfere with the linkage for the foot brake.
This is the backside of the above shot:
Here's the plate that hangs on the socket head screws mounted to the VFD.
And this is just the back side of the above:
Here's the bracket in the pedestal:
This is the VFD and the braking resistor during the installation process. Not all connections made yet obviously:
Now some may be saying what about keeping crud out the of the VFD since it is sitting just below a hole in the pedestal through which the brake linkage passes. Here's what I came up with. A piece of Plexiglas that hangs from the lip of that opening and extends down to cover the VFD and keep what ever might fall through this opening from getting to the VFD.
Here's the top of the Plexiglas and how I made it hang from the lip. Again, made from scrap
And here it is hanging down in front of the VFD. May be hard to see in the photo:
Looks like I'm at the upload limit for photos for one post.
To be continued...........................
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