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Help needed with upgrade to 650 x 500 laser engraver

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donwatson:
I have recently (a month ago) started to upgrade my laser engraver.
I ordered 12 black 'Delrin' wheels, a new Eleksmaker Mana 3.2 board and a new Eleksmaker 2.5mW laser module. All from BangGood.
The wheels arrived today (the board is scheduled for tomorrow (Thursday) and the module for Saturday ??) and I find the new wheels are twice the thickness of the white original ones, that means the existing spacers are the wrong size to fit my machine.
My first question is where can I purchase the correct spacers ??? I have had a look on the Eleksmaker site and can find no mention of them anywhere. I have been on the BangGood site and had to give up with them. Ideally would like to deal with Eleksmaker and am deeply sorry that I didn't contact them before I started on this upgrade.
I am a retired Toolmaker and can make the bushes/spacers on my lathe to the correct dimensions but as the weather is not too good here for working in the shed I would rather order them from somewhere reliable.
Any help will be appreciated.

take care
Don W

ggallant571:
Post some specs on the old & new wheels. Will the new wheels ride nicely in the v-groove?  Is the axle centered ok?

On my A5 machine the spacing on X-Carriage doesn't much matter so you can probably use it to test the fit.
 

donwatson:
Hi George,
The old rounded white wheels are 5mm wide (bearing size), the new black wheels are 11mm wide and fitted with double bearings.
The original spacers on the X axis were 10mm and 12mm setting the wheels off centre.
This is getting harder to explain, but I don't know why they were set like that.
The Y axis is a single spacer 10mm long. I will need to reduce the length of this spacer to 7mm to set the wheel in the same place on the track, an easy enough job.
I will see if I can sketch up something but I will probably go and make up spacers to suit myself.

Don W
I have attached a pic that nay explain.

ggallant571:
Don,

I had a similar arrangement on my X-Carriage. When I updated the wheels the new wheels were approx 0.7mm larger that the old. The result was a much to tight fit. Our local hardware store carries both US and metric nylon spacers along with precision flat washers. I don't think the absolute spacing in critical. Just be the same on all 4 axles on each side.

There is a post about a 3D printable adjustable wheel fixture.

I tried and failed with eccentric nuts. Available from openbuilds. You need to get both sides the same. In the end I 3d printed the 2 X-carriage plates with the "calculated" spacing. Took 2 tries!!!

A machinist friend offered to turn 5mm round stock into eccentric axle rods with threaded 3mm on each end and a screw drive slot for adjusting. If I need to do it again that will be my first choice. I have since built 2 core-xy fixtures and the wheel problems disappeared.

donwatson:
Thanks George,
I have the idea worked out and will see what I can make up.
The fact that the X axis has long and short spacers threw me as it meant the 2 acrylic plates had to be different offsets from  the aluminium extrusion, I don't know if this was to balance the weight of the stepper motor against the weight of the laser module ?? or am I over complicating things here ??

I did recall a post about a 3d printed adjustable wheel fixture with an adjusting screw in the middle that gave a very good result for setting the fit of the wheels. I will look further into this.

I will re-machine  the spacers on the Y axis as that is straightforward.
I will weigh the stepper motor and the laser module and see if there is any great difference that may twist the X frame backward/forward on the aluminium cross extrusion.

Don W

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