PDV PT-SD408 Z-Axis Linear Stage - any experience?

Ray Jade · Post by **Ray Jade** » Mon Apr 20, 2020 11:42 am

Hello All

I'm trying to make the best of the current lock down and take up some photography again.

One of the frustrations I've revisited over the weekend is the lack of vertical - Z-axis - control and precision. I've avoided low cost lab jacks as they've seem pretty flimsy and I can't justify spending on the proper kit from the likes of Thorlabs.

I spotted a interesting looking jack from a number of Chinese sellers priced from GBP 90 / US$ 120 eg: https://www.ebay.co.uk/itm/Precise-Manu ... SwM91acVh1

Search term "PT-SD408"

There is a version with an added height scale (PT-SD408S) for a little more money and larger version (120mm vertical = PT-SD409) for a lot more money.

If anyone can advise if this unit is worth the spend v's a GBP 15 / US$ 20 small labjack, I'd be grateful for any input.

I assume that I'd need to adjust X/Y-axis specimen positioning after Z-axis to allow for horizontal displacement?

Do I have other realistic options?

Thanks for your help

Macro_Cosmos · Post by **Macro_Cosmos** » Mon Apr 20, 2020 12:18 pm

Not sure about others' opinions, I think it's pretty mediocre. I used to have one.
The branding is a sticker, there's lots of other brands that offer the same labjack. You might find a cheaper one.

The centre doesn't change much, but there is very visible wobble beyond 10x. When it comes to both ends, the stage slacks off a lot.

The ruler scale was useless for me.

Besides having convenient threading, I don't think it's worth the premium over ordinary $20 labjacks used in high school chemistry labs. If they fix the wobble or at least make sure it's impossible to go beyond the extremes causing instability, and not being too liberal with grease (well, on my unit, yuck), it would be alright.

You might prefer something like this:
https://www.ebay.com/itm/SIGMA-KOKI-Z-A ... Sw5R5dOlas
Sometimes you can get them for cheap.

Thorlabs ones are really good, love it, but yeah it comes with a premium. Why not get a film enlarger and salvage the stage? Those work really well and pop up on flea sites for ~$50 as junk from time to time. Lots of other stuff in it, such as condenser lens that are worth salvaging too.

Ray Jade · Post by **Ray Jade** » Mon Apr 20, 2020 1:39 pm

Macro_Cosmos wrote:Not sure about others' opinions, I think it's pretty mediocre. I used to have one...

Thanks Daniel - much appreciated; that's enough to put me off. Shame as it looked just about expensive enough to be worth a punt.

Macro_Cosmos wrote: You might prefer something like this:
https://www.ebay.com/itm/SIGMA-KOKI-Z-A ... Sw5R5dOlas
Sometimes you can get them for cheap.

Good hint - shows my lack of experience that I didn't search "Z-axis stage" or similar.

Appreciated.

ray_parkhurst · Post by **ray_parkhurst** » Mon Apr 20, 2020 7:39 pm

I use a smaller 40mm stage in my setup for precise manual focusing. There are a few similar available. Hopefully they will ship to you:

https://www.ebay.com/itm/40x40mm-Z-Axis ... 3734903796

Macro_Cosmos · Post by **Macro_Cosmos** » Tue Apr 21, 2020 3:24 am

Ray Jade wrote:
Macro_Cosmos wrote:Not sure about others' opinions, I think it's pretty mediocre. I used to have one...
Thanks Daniel - much appreciated; that's enough to put me off. Shame as it looked just about expensive enough to be worth a punt.

It's pretty well made, just mediocre mechanics. It's like a nice car shell but the internals feature a $20 IKEA office chair.

ray_parkhurst wrote:I use a smaller 40mm stage in my setup for precise manual focusing. There are a few similar available. Hopefully they will ship to you:
https://www.ebay.com/itm/40x40mm-Z-Axis ... 3734903796

That's a cute little stage, 10mm is plentiful, enough for vertical setups.
If anyone wants more than 10mm, just add a coarse Z-axis stage such as a $20 labjack from science stores, or as I've said, an enlarger rod thingy which I prefer.

Ray Jade · Post by **Ray Jade** » Wed Apr 22, 2020 2:29 pm

ray_parkhurst wrote:I use a smaller 40mm stage in my setup for precise manual focusing. There are a few similar available. Hopefully they will ship to you:

https://www.ebay.com/itm/40x40mm-Z-Axis ... 3734903796

Thanks Ray. This seller offers "Worldwide" but then excludes almost anywhere but the US! I'm looking at similar options including the second hand Sigma Koki units Daniel mentioned.

No hurry whilst I experiment with a vertical specimen setup.

Much appreciate the quick and helpful suggestions.

ray_parkhurst · Post by **ray_parkhurst** » Wed Apr 22, 2020 5:17 pm

Ray Jade wrote:
ray_parkhurst wrote:I use a smaller 40mm stage in my setup for precise manual focusing. There are a few similar available. Hopefully they will ship to you:

https://www.ebay.com/itm/40x40mm-Z-Axis ... 3734903796
Thanks Ray. This seller offers "Worldwide" but then excludes almost anywhere but the US! I'm looking at similar options including the second hand Sigma Koki units Daniel mentioned.

No hurry whilst I experiment with a vertical specimen setup.

Much appreciate the quick and helpful suggestions.

I have one of the Sigma Koki units and it is excellent, very high quality and worth the extra $ if that's "all" you can get delivered to you.