Robot Arm

[Arbutus]

I've been making up a list at AliExpress since I need 32 different screw types. I think I will finish the spreadsheet of all the screws and get Spaenaur to quote but for this cheap (well not really cheap) robot arm I'm not sure I need an extra 87 screws if I have to buy a box of 100.

Even McMaster Carr can supply these of which I need 13 according to the parts list.
View attachment 34830

Where AliExpress wants 1/2 of that but of course I'll have to probably wait a month where McMaster Carr will ship on Friday.
View attachment 34831

I wonder if the quality is any different. Shipping is about $25 from McMaster Carr.

I've been purchasing metric screws (Black oxide; hex socket) from MMC for years and I have a substantial inventory. Their screws are significantly harder than the offshore cheapies. But the main reason I keep using MMC is that their products are consistent and I can rely on them for the same quality over many years of orders.

If you only need a few dozen screws John, just DM me.

Don

 

[jcdammeyer]

I've been purchasing metric screws (Black oxide; hex socket) from MMC for years and I have a substantial inventory. Their screws are significantly harder than the offshore cheapies. But the main reason I keep using MMC is that their products are consistent and I can rely on them for the same quality over many years of orders.

If you only need a few dozen screws John, just DM me.

Don

Thanks. I know I want some just for general inventory. I already have a supply of some sizes. Just not everything for this Robot Arm. I've got an order coming from MMC but it's for mostly work-work stuff. I usually add some of my own inventory onto it to save shipping. Impressed with their delivery statement. Theoretically I'll have the stuff on Friday.

 

[jcdammeyer]

How about that. Ordered from McMaster Carr Yesterday and they arrived here just before 7PM. Now I have no excuse to finish building the power supplies for my client. I also received the 3 bearings, slotted shaft and key for the Robot Arm. Now it's just screws, machined castings and motors/gearboxes/encoders left to procure or build.

But tomorrow I have to mow the lawn... again...

 

[Janger]

How about that. Ordered from McMaster Carr Yesterday and they arrived here just before 7PM. Now I have no excuse to finish building the power supplies for my client. I also received the 3 bearings, slotted shaft and key for the Robot Arm. Now it's just screws, machined castings and motors/gearboxes/encoders left to procure or build.

But tomorrow I have to mow the lawn... again...

Ordered yesterday and they are here overnight! From the US! I’ve ordered from them before and been similarly impressed. Expensive though.

 

[jcdammeyer]

Ordered yesterday and they are here overnight! From the US! I’ve ordered from them before and been similarly impressed. Expensive though.

It was impressive. Here's the tracking info. Shipping was $21.84. One has to wonder why, if it's on the vehicle at 9:08 AM that it takes until 6:32PM to reach my FRONT DOOR.

 

[Susquatch]

One has to wonder why, if it's on the vehicle at 9:08 AM that it takes until 6:32PM to reach my FRONT DOOR.

How many Tims are there in Victoria?

 

[LenVW]

It was impressive. Here's the tracking info. Shipping was $21.84. One has to wonder why, if it's on the vehicle at 9:08 AM that it takes until 6:32PM to reach my FRONT DOOR.
View attachment 34871

Hamilton, ON to Victoria, BC . . . in less then 24 hrs . . . for $21.84 .
I think that is fair.
. . . next time, ask him to pick-up a Medium Double-Double . . . also !!

 

[Tom O]

Hamilton, ON to Victoria, BC . . . in less then 24 hrs . . . for $21.84 .
I think that is fair.
. . . next time, ask him to pick-up a Medium Double-Double . . . also !!

I’m having one as we speak.

 

[jcdammeyer]

Used the new 3D printer to make the last part of the base and connector box+lid. Especially since I now also have all the connectors. With all that happening and the garden tractor finished I finally succumbed to temptation and ordered the stepper motors c/w planetary drives and stepper motor drivers. Still need to get 4 more encoders.

And cast the 1/2" plate that to which everything mounts.

 

[LenVW]

Used the new 3D printer to make the last part of the base and connector box+lid. Especially since I now also have all the connectors. With all that happening and the garden tractor finished I finally succumbed to temptation and ordered the stepper motors c/w planetary drives and stepper motor drivers. Still need to get 4 more encoders.

And cast the 1/2" plate that to which everything mounts.

Keep on testing the limits of your abilities - John.

One of my mentors used to say “Novel designs are your best ideas - unproven”.
The fun part is making prototypes and improving them along the way.

 

[jcdammeyer]

The motors have arrived. Just need to order the other 4 encoders. I was holding off in case I could use some I have on hand but the mounting holes are only for the CUI type.

Theoretically I can hook up all the electronics and move motors.

 

[LenVW]

The motors have arrived. Just need to order the other 4 encoders. I was holding off in case I could use some I have on hand but the mounting holes are only for the CUI type.
View attachment 36124
Theoretically I can hook up all the electronics and move motors.

I can remember using ‘Hohner’ Rotary Encoders back in 1995.
Who are the main sources in the current market ?

 

[jcdammeyer]

I can remember using ‘Hohner’ Rotary Encoders back in 1995.
Who are the main sources in the current market ?

CUIDevices is the big player for the low cost systems. US Digital still makes them too. The two I have cost me $150 each I think. And they ended up being really sensitive to noise so I finally swapped them out for the CUI. Then the real problem with the one DC servo showed up which had been masked by the encoder noise.

AMT Modular Encoders | Same Sky

Same Sky's AMT Series is a range of rugged, high accuracy modular encoders available in incremental, absolute, and commutation versions. Learn More

www.cuidevices.com

Encoders

US Digital designs and manufactures optical encoders, inclinometers & motion control components. Our complete product line includes either absolute or incremental optical encoder & inclinometer products, stepper motors, PC interfaces, and digital readout.

www.usdigital.com

In the hobby market the far east ones with 1/4" shaft and bearings for under $10 (compared to the $400+ way back) have made it possible to create the electronic gearing often erroneously referred to as electronic lead screws.

https://www.aliexpress.com/item/1005005071771659.html?spm=a2g0o.productlist.main.1.5f1912920tMHBV&algo_pvid=abcd1846-fe8f-4e24-a415-e55479b67693&algo_exp_id=abcd1846-fe8f-4e24-a415-e55479b67693-0&pdp_npi=3%40dis%21CAD%2110.14%217.61%21%21%21%21%21%40211bd8be16881591390947379d07c3%2112000031526886195%21sea%21CA%21718821561&curPageLogUid=qjXMk7BntWMh

 

[LenVW]

I had a quick look at the LINK you included.
With the CICK product line, you could build several servo-driven applications.
The prices of these East Asian components are a fraction of other suppliers.

• 
  
  

Photoelectric Incremental Rotary Encoder 38S6G5-B-G24N 50/100/200/360/400/500/600PPR AB 2 Phase DC5-24V NPN Optical Encoder​

Price Each: C$11.35
Shipping fee: Approx. C$10.00


Color: 1000PPR

Rotary shaft encoders in the 1990’s were $500/pc.

 

[Arbutus]

These Asian high resolution encoders are remarkable pieces of equipment for under $15. I have used them for speeds up to about 1000RPM without any problems. A 1200 PPR encoder pulses once per 0.3 degree which is significantly better resolution than the units I bought just 10 years ago which cost fifty times this much!

 

[jcdammeyer]

There are several reasons for the discrepancy. The obvious one of course is economic slave labour but that's not the entire reason. Technology changes are probably the biggest reason.

Just like the National Semiconductor SC/MP Kit which was my first micro. The CNC equipment, if a company even had one, ran with paper tape. My first Comp. Sci. University year was with punch cards and AlgolW or the novel special terminals for APL.

Fast forward, if you can call it that to the late 90's and LinuxCNC known as EMACs along with Windows Programs like MACH2 and then MACH3 at the turn of the century started to make it possible to automate things that in the past required skilled labour.

When I started my ELS project in 2006 an encoder disk with a large enough bore for my South Bend was $75US but I had to buy 100 to get that price. Hence like MACH2/3 a 1 PPR encoder was the only solution that could keep the price including stepper driver for the Z axis at $150US. The types of modules like the Arduino didn't exist. And the price of toothed belts, pulleys and a ball bearing'd encoder was still up in the $200 range.

Fast forward to around 2010 and later and we have a number of CNC type machines. You could order a MACH3 Break Out Board that came with a tiny CD holding a pirated serial numbered copy of MACH3 to run on WIN-XP. It was no longer even close to being economical to build a foundry and cast a Gingery Lathe because the far east cast iron 7x12 or 7x14 were so incredibly cheap compared to even just a decade ago. All due to the far east using CNC to cut labour costs even further.

So now the encoders required for so many robot and other control projects. My contact at Bergerda told me that they still use Japanese encoders because they feel they are better and therefore the prices on their motors are slightly higher than their competition. There's still room for quality. And they sell a lot into the garment fabrication industry like looms etc. So there's another area that North America let slide rather than automate.

My favourite peeve back when the Alberta Heritage Trust Fund was large was that the government decided the money would be well spent on creating the Kanaskis Golf course bringing in, from out of the country, white sand to look like snow for the sand traps. I would have liked to see the money put into building VCR's from scratch.

Now before anyone jumps in and says "Look what happened to VCRs" I want to stress building a VCR from scratch means from nothing but the raw materials are imported. So an infrastructure is built up to make tiny screws, metal stamping, plastics, motors, tape heads, wire, cable etc. The change to CD ROM drives and then DVD and then BLU-RAY etc. would be easy as would an automated fabrication of Cell Phones and all the infrastructure you don't see behind the scenes for cell service.

Creating an infrastructure based on small companies instead of the giants that sell out to the biggest off-shore buyer is a mistake Canadian Companies do over and over because being a hewer of wood and carrier of water appears to have a higher profit until the wood is gone and the water polluted.

Anyway I've diverged from my robot arm discussion. Next post will be a photo of a pattern and casting.

 

[LenVW]

I did check and Horner is still in the business.

PRODUCTS | Hohner Automation

Hohner Automation has a wide range of incremental and absolute encoders, different lineal measuring systems and all the accessories that you may need for the correct assembly of our sensors.

www.encoderhohner.com

Lots of Canadian breakthroughs have fallen into the scrap heap.
Some startup businesses cannot arrange the supports they need while their operations grow at an adequate pace to satisfy banks and investors.

When I was on a development team in the 1990s, our product was attracting attention from a group of American companies with lots of financial resources, operational facilities and markets to exploit, but, just when we were ready to promote our products and start the commercialization across North America, our owner had health problems and the new owners
could not be convinced to take the leap from commodity supplier to industry developer.

Business development takes time, capital investment and a little luck.

 

[jcdammeyer]

A lot of luck.

 

[jcdammeyer]

So after practising with the mill and CNC to make a stepper motor encoder holder back plate I thought it was time to get back to the robot arm.
Used the band saw to rough out two pieces of surplus material. Then square off and size the blanks to fit the drawing dimensions.

The next step is to use the CNC from the drawing to create the slots and holes.

After that I guess I'd better order the screws so I can mount the stepper motors to them.

 

[jcdammeyer]

First screw up. Totally expecting that the hole wouldn't be round but hoping that the backlash compensation would fix that.
Mistake #1. Using conventional milling instead of climb milling. Bad surface finish.
Mistake #2. Way too fast a feed for spindle RPM even though I was way under the recommended values for the 1/8" mill.
On the second slot I think it pulled against the backlash again and snapped the cutter. The first slot was not straight for the same reason.
Cut back on speed to 5 IPM and 2850 RPM. Max depth of cut 0.050" and switched to climb milling. Much nicer finish and the slot stayed straighter.

The hole in the photo looks more oval than it really is because of the cell phone camera angle.

For the next one I'll use slower speeds and climb milling and pull out the boring head to bore the 25mm hole.
Alternatively put it in the 4 jaw chuck on the lathe and bore it to 25mm and close fit to the motor. Then onto the mill and center on this hole and finish doing the other holes and slots.