How would you do this?

[Inferno]

I'm getting ready to add the stepper motor to my X-axis on my lathe (combo).
When I bought the machine it had 4 bolt holes at the end of the way that I used to mount the DRO. It took a while to set it up to be perfect.
Those holes will be the best place to mount the stepper motor. I made a bracket for the stepper and being able to mount to those holes.
The mount can work fine on top of the bracket for the DRO.
The problem. To adjust the belt tension on the stepper I will need to loosen those 4 bolts each time and that can/will affect the DRO mount position so it would need to be reset. That would change the belt tension and it will be a battle.

My first thought is to drill a pair of securing bolt holes to the original bracket (in top picture). Since it's already there and in place, I could just drill a pair of M5 holes and tap directly into the cast iron of the lathe. It won't affect the durability or any other feature of the lathe.
If there's a better/easier way to do this?

Ignore the mess

 

[GeneT45]

A tensioner (tensioning pulley) might be easier to mount. You really don't need a lot of tension with a toothed belt, so a free arm with a roller on it and modest spring tension would probably do. The arm could probably be mounted to your plate - it should be a one-and-done deal.

GsT

 

[Inferno]

A tensioner (tensioning pulley) might be easier to mount. You really don't need a lot of tension with a toothed belt, so a free arm with a roller on it and modest spring tension would probably do. The arm could probably be mounted to your plate - it should be a one-and-done deal.

GsT

That was my first instinct but there's two issues with it.
The first is that there's just not enough room for a tensioner.
The other is that I've had problems, in the past, on industrial machines, where the accuracy varied when the pull was on the tensioner side. Not by much but on those machines it made a big difference as there was an encoder on the slave gear.

 

[GeneT45]

That was my first instinct but there's two issues with it.
The first is that there's just not enough room for a tensioner.
The other is that I've had problems, in the past, on industrial machines, where the accuracy varied when the pull was on the tensioner side. Not by much but on those machines it made a big difference as there was an encoder on the slave gear.

Sounds like a design issue. The encoder should always be on the thing you actually wish to measure - ideally a linear encoder for travel, or at least a rotary encoder on the lead screw.

GsT

 

[Inferno]

Sounds like a design issue. The encoder should always be on the thing you actually wish to measure - ideally a linear encoder for travel, or at least a rotary encoder on the lead screw.

GsT

I don't disagree. I can't tell you how many times I had to mess with stuff on those machines due to weird design issues. They were made in the Netherlands and some parts were just very under engineered and quite a few that were over engineered.