Greg,
Leko here on the forum found a great solution for holddown for my table. Slatwall. It's available in all sorts of materials - PVC, MDF, etc. and has t-slots on varies centers. Or, since you have a cnc table, by a t-slot bit and make your own!

Sean

Ahh Interesting,

I'll look into it!

Thanks

Sean,
Great idea, did you cut your own? How did that go on the CNC?

slatwall
t-slot cutter

to make your own I used a 2 step milling of a sacrificial MDF sheet on top of the spoilboard.

1/2" mill bit, followed by a T-slot cutter.
Then t-slot bolts and hardware from rockler.com

With that particular job, you could drill the countersunk screw mounting holes first (when it is still part of the original square blank), then screw the blank down to the table using those holes. Once fixed to the table, all the other cuts can be done safely without the job moving or having to worry about running into a clamp.

Alan,
Also a neat feature that MM users may not know, you can actually Identify the clamp areas in your cut file so the the machine won't hit the clamps. Or at the least, the file will pause so you can remove or move the clamp and progress on.
...Even LazyCam has this feature!

Sean,

My spoil boards are 3/4 inch. Will this be thick enough for the T-slots?

Should be....But you may want to actually want reinforce the t-slots with the slatwall PVC strips made to reinforce the slots. This will allow for you to surface the top flat and still have a "strong" slot for holddown.
Sean

Are you running the T-Slots the length of X or Y? What kind of distance are you putting between them?

I like the idea of putting the hold down into the code. That is a nice feature.

Are you sure HSS was the problem? maybe it was slow feedrate or cut too deep and the mdf chips (powder?) did not had an easy exit way and stuck to your cutter.


Pablo

Hi PEU,

It's probably what you said, slow feed rate combined with high rpm (24,000)! I cut the ends of my spoil boards today with RPM 16000 at a bit higher feed rate and there was no problem.

Any suggestions on how to hold down the spoil boards? Spray on glue? I have no idea!

I use a roller and Elmer's wood glue.
Put a bunch of temporary screws or weight on top, then when dry, remove screws and weights.
Surface the MDF...when the sacrificial board gets to thin, I just add on top again!

Woodglue (elmers, titebond etc) spread on with a roller, position board and weigh down with sand bags, timber, what have you...

Elmers Wood Glue.... cheap and it works.

Got my Limit Switches finished up today. I am using 3 switches wired in parallel, normally open for limits and homing. I used button top bolts for my limit stops. In the future I will probably switch to proxies but for now this is working great.

Here's a quick vid: http://www.crosstrainer.ca/downloads/homing.mpg

Had a real nice visit with my buddy Greg yesterday afternoon, here is a pic of us and the machine. Greg on the left and Heath on the right. Big blue thing is of course the Mechmate! :)

Damn Heath, ain't we pretty!:) Thank god for brains or we'd be sunk :eek:

Here's a quick update, I changed over all my pinions to 20 tooth, and upgraded my grub screws to 1/4 28 thread. Pinions are now staying nice and tight. Speeds are excellent, lots of torque, I think the changeover is a great idea (unless you like to jog at 1500 IPM). I finally installed a gas strut for my Z (getting rid of those pain in the a#$ springs). I'm getting a solid 13.77" inches of Z-travel (limit of the strut).

As a fun test, I cut out a cub-car for a friend. The model was just a primitive mesh that I imported into rhino and then used rhinocam to process into gcode. One rough pass, then a finish at 45 and finish at 90. My friend went away really happy, especially since another club always manages to out-do them every year, this time they have a weapon :)

The weather is finally getting warmer here, I'm looking forward to some good long runs!

Greg,
Not sure if the brains make up for my mug. :) I would need a PHD. So where are the cut comparison pictures for 20t and 30t pinions? :)

Hi Heath,

Cut quality between pinions is minimal (it probably would show up more with 1/8 and smaller cutters), but with 3/8 to 1/2 cutters, you can't really see any difference; the acceleration factor is the key to smoothness when doing any point to point cutting as we discovered.

First, let me say that it has been just fantastic to see the progress that everyone has been making on their MechMates, what a great group of people!

For my latest update, I finally finished my T-Slots. What I did was glue down the first board, and cut the bottom of the slots. I then glued on the upper board and cut my center slots. The standard 3/8 T-Slot bolts fit well, but even better, the leftover cut piece from my aluminum rails fits the slots and they run the full distance of my slots. So I am drilling and tapping holes into the aluminum to use with the standard hold-down kit. That will give me alot of hold down strength.

The toughest part was cleaning out all the MDF dust from the slots!

Here's a few pics:

Greg,

The slots look great. Nice touch using the aluminum.

Did you try blowing the slots out with you compressor?

Sound like a dust collection unit is next?!!!!

Greg,
That looks really good. Now you will have to show everyone stuff you are cutting with the new hold downs. :)

Hi,

Sorry for my language skills...but...
at the one of your pictures I saw bottle of beer

http://www.mechmate.com/forums/attac...d=123363937 7

.... what is the name of that bear? "Zubr"? It's a bear from POLAND :)

Hi Nils,

A vacuum system is most certainly in my near future. But first I have to move the MechMate into the room that you can see at the back right of the above picture. Should be interesting!

Heath, As soon as I get my ball-nose bits in the mail I'll be starting to cut some interesting things :) I am now making some long clamps for use with the aluminum in the slots. Looks really promising.

And yes Berzer... it is Zubr, the king of all Yak beers... my favourite beer of all time!

Hehe... it's nice to hear that you like it. But I'm supprised that this bear is available in your country :)

Zubr is brewed by the Dojlidy brewery, which is owned by Kompania Piwowarska, which is owned by SABMiller, which originated as South African Breweries. It must be a good beer! :D

True...true :cool:

Console
 

Hi everyone,

I finally got to put some time in on my Mechmate again. This time I got it moved to its permanent home and leveled it. I made up a console out of some scrap bits I have kicking around; it turned out simple but effective me thinks.

Heath -- while testing I noticed that my MM runs rougher with the 20 tooth pinions; I tried everything, port speed, steps, velocity, acceleration, CV modes, but no luck getting acceptable smoothness... I also cleaned the rails and wheels -- it made a small difference. I disconnected the motors to test the gantry and y cars :both roll very smoothly!

I'm going to leave the 20 tooth on the Z, but change back to 30 teeth on the X and Y and see how that works. Will update with results.

Hope all is well, Greg

35 Tooth gears
 

Greg,
I have some 35 tooh 20 DP .500 shaft gears if you would like to try them for comparison.
Buzz

Greg,
Is that new paint on the shop floor? Or is it just cleaner than the last time I saw it? :eek:
The machine is looking good. Let me know what you find on the pinion gear comparison.

Looks nice Greg!

Small gears will run rougher under the spring-loading than bigger gears, but it doesn't necessarily mean that the cut quality is going to suffer. (From what I've heard, the smaller gears give the smoother cut, even though they may be noisier)

Hi Buzz,

Hi and thanks for the offer! I think my 30 toother's will suffice for now. Are you the Buzz that Heath has been telling me about? It's great to have another MM builder in the local area; we have enough people for a MM club :cool:

I just haven't gotten around to wrecking that part of the floor yet :) In the SmoothStepper forum, dmoore was warning that 20teeth pinions with 7.2OM are approaching the limit of the parallel port 42khz. I'm really interested in trying out the SmoothStepper when I get some more feedback on how it is working. Gerald any luck yet?

Thanks, Greg

I heard from son Sean this morning that he has got a Smoothstepper working a few days ago.

I am the one that Heath knows. Heath fixed me up with the parts to get this started. I did the cabinets and millwork for the Macs Milk store at the corner of Abbott and 15 hwy. a few years back. :)

Gerald,
Was that Sean D or Sean R?

Buzz, Greg,
Maybe we can start the OMMBG, Ontario Mechmate Builders Group? Catchy name no? :)

Heath, thought it might confuse, so I said:

:)

I swapped over to the 30's and things smoothed out quite a bit. I'm excited about the Smooth Stepper though. I think that would convince me to put the 20's back on.

We're going to have to figure out a get together for the three of us sometime this summer!

Gerald,
I never noticed that when I read it the first time. :)

Heard today that the Smoothstepper is not going that smoothly . . . .

SmoothStepper looses communication with PC in the Troubleshooting Forum