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Messages - carolynsdad

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Maybe I'm looking in the wrong place ?
Is it L1 or L7 next to the power connector and switch?

General Discussion / Re: Link for better same spec wheels?
« on: March 06, 2017, 12:29:14 AM »
Mmm..Hands up all those that have had NO trouble with bearings.

hands up - no trouble with bearings

General Discussion / Re: Link for better same spec wheels? -(CHECKED)
« on: March 05, 2017, 09:19:30 AM »
I just realised that the white wheels look identical to the former of those on our shower sliding doors, will check on diameters when I get a chance.

I checked but they are narrower and have a plain bearing, no use.


Z Axis / Re: 7000mw laser
« on: March 02, 2017, 12:22:48 AM »
My home-brew slide mechanism is not very precise. Started building a second machine with linear bearings on 8mm rod. New scheme for Z but I have a problem that is completely eluding me, how to tell if the laser beam is perfect (or close to) vertical from the work. Any tilt results in a wide cut. I'm not sure that rotating the adjustment lens keeps it vertical. Any suggestions?

Are you using 8.00mm course or fine thread rod? Course will have a pitch of 1.25mm; fine is 1.00mm. 1.00mm would seem ideal and the finer the better to give minimum backlash so how about M5 fine pitch. Source

Just tossing in some ideas ... I think I would look to have any mechanism as light as possible and short threaded rods (one left thread and one right) either side of the Z carriage (connected by a 1:1 gear head and knob on top) to keep the mass of laser and carriage as close to the rail as possible to minimise off-axis loading. is a great place for threaded materials in UK. Next to find a small precision linear rail mechanism at a sensible price; not easy it has to be said!

PS - Admin - perhaps move this discussion to a dedicated Z-Axis thread (no pun intended!)


Projects / Re: Engraved part numbers
« on: February 28, 2017, 09:43:32 PM »
PWM isn't as sensitive compared to TTL so the dynamic mode isn't as effective but may still work.

What do you mean Zax; I can't see how you can compare TTL, which describes the interface voltage levels of a signal representing high and low levels (basically fixed at 0V and 5V), with PWM which is the form of modulation controlling the time the signal is at those levels (fully variable between 0% to 100%)?

General Discussion / Re: A3 End Plates
« on: February 25, 2017, 07:04:29 AM »
I came up with a quick and easy solution that involves cutting two aluminium plates, drilling six holes and modifying spacers.

The plates are secured by existing wheel bolts and have the centre holes slotted so that the in-line bolt acts as a pivot point and the centre bolt provides verticle adjustment of the repositioned outer wheel. I needed to fettle a couple of spacers from my spares box to be the same length as the existing spacers plus the thickness of the end plate.

The difference it has made to stability of the carriage is huge, job done.


Laser Modules / Re: 3.5W Laser Head with TTL Driver
« on: February 23, 2017, 05:46:18 AM »
What do you use for schematic drawing tools?
I used DesignSpark for the first time on this; not done any for years and then it was pencil and paper!

Laser Modules / Re: 3.5W Laser Head with TTL Driver
« on: February 23, 2017, 05:00:06 AM »
You are welcome. Something that is quite apparent is that the the manual soldering of trim pots, connectors and caps is appalling but the SMDs are OK; they don't seem to be able to put the base of the components down on the board before soldering so most flapped about a bit until I reworked it.

Laser Modules / Re: 3.5W Laser Head with TTL Driver
« on: February 23, 2017, 02:52:39 AM »
As promised a while back here is the result of my reverse engineering of the driver board that came with our 3.5W laser kit.
Schematic and views of top and underside.

A few notes:
1. I have not been able to find any marking on the Zener diode Z1 which is going to be something in excess of 5V to clip spikes and provide protection.
2. The SMD capacitors are not marked but my guess is that they will be in 10nF
3. There are positions for fixed resistors instead of trim pots but nothing fitted
4. The inductor is simply maked 60 so guessing it is 60uH
5. I mused a bit over the output of the LM358 (U1) but this really is how the circuit appears so must provide controllable bias to Q3
6. The J3y transistors could probably be replaced by KST2222A (data sheet attached)
7. I have also attached a couple of other data sheets and reached the limit but the LM358 is easily available, note only half is used.


General Discussion / A3 End Plates
« on: February 22, 2017, 03:22:17 AM »
Our A3 machine has Y axis end plates that carry five wheels (see photo) where the two on the bottom are placed close together instead being inline with the two outer top ones.

The carriage has a terrible amount of play; it can be rocked just over 1mm on the top wheel which translates to significant laser dot position movement .

I cannot understand why the design placed the lower wheel where they did, exacerbating the effect of free play, and to make matters worse cut off some of the acrylic preventing a new hole from being drilled. Anyone in UK making replacements with that lower right wheel moved below the upper one?

I suppose I could cut off the piece with the lower hole and make an adjustable plate to reposition it ... now there's a thought!

An additional point is that the top central wheel seems to be rather pointless as it will almost certainly not be touching the track or be adding friction. I see that in a Banggood video that haven't fitted it.


I forgot to add the photograph, here it is.

T2 Engraving / Re: I need help!
« on: February 18, 2017, 01:21:53 PM »
My laser also fires for about 2 seconds on burning power everytime I go into the control laser screen, How do I stop that?

It depends on what board you have there for driving the laser; ours (shown below) came with the 3.5W laser and my solution to the problem is detailed here:,1391.msg18049.html#msg18049


General Discussion / Re: New lens
« on: February 16, 2017, 12:38:21 PM »
Teflon tape is a very short term fix.  Adjust it a couple times, and its useless.

Better alternative is to coat threads with clear silicone with your finger.  It basically adds an oring to the entire thread base, and doesn't wear nearly as fast with adjustments.

My advice is to keep anything containing silicone well away from optics; it is a well known contaminant which even just as a gas can leave a non-volatile silicate surface. This can degrade the optical properties of the surface and is very hard to remove.

Does this mean that the power ground and ttl ground are not connected on the laser diode power module?

If the design is similar to mine with the 3.5W diode then you are correct, the laser does not use 0V from the controller board as both the high and low sides of the laser supply are controlled in the laser board. I am still reverse engineering it to make the circuit available to all but time is not on my side at present.


General Discussion / Re: First large greyscale attemp
« on: February 04, 2017, 11:33:22 PM »
Excellent work. It would be great to know what settings and material you used to obtain this level of clarity.

General Questions / Re: Laser stability problems on Banggood A5 2500mw
« on: February 04, 2017, 10:07:53 AM »
Is the laser lens steady on its thread or does it wobble a bit?


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