Can I reasonably make these parts with CNC router?

[gravelbar]

I own www.emriver.com; we are small (6 people) and make world-changing educational models and science tools. Really struggling now with production and ways to do it -- lots of orders! I am a decent machinist but now trying to decide whether to buy a CNC router. Please see attached photo; the HDPE part is about 2" tall and 1.25" in the other two dimensions. Can I economically make batches of these with a CNC router considering that there are at least two faces or axes that need machining? I now do these manually on a small mill, but time to ramp up and contract out or do it better in house. I really appreciate any help! (And part is for this thing, if you're interested: http://www.emriver.com/?page_id=2629)

[chiloquinruss]

Without actually knowing which parts in the pix you are referring to, I can see many of those parts in the pix being made on a Bot including all of the clear stuff. Please show us a pix of just the finished pieces all by themselves so we can better give you an answer. Russ

[zeykr]

Looks like you would cut from 1.25" material with a groove for the gate and drilled through hole for the shaft, then cut out the shape. Next I'd probably cut the bottom groove for the slide using a dado blade on the table saw using a jig to hold it.

Alternately (kinda depends on size the material comes in) you could make a jig to hold a 2.5" tall by 1.25" wide by 3'? piece of material and cut the dado that would be in the bottom, then lay the dado'd piece on it's side in another jig and drill the hole and cut the slot for the gate and cut to shape for several parts at a time.

Basically, yes I think it can be done with a couple jigs but ultimately will depend on how many you need to cut as to whether it's practical.

[gravelbar]

Sorry Russ; the two larger white HDPE parts that hold the shaft and have slots on the bottom to engage the aluminum extrusion on on the sides to guide/hold the polycarbonate "gate" that's turned by the shaft/rack/pinion.

I see all kinds of sheet stuff here and on YouTube vids, etc, but so far no parts like this that would have to be turned at least once to be routed. Thanks!

[gravelbar]

Ken, the mulitple jig/steps thing is what I do now, but with a mill; it works fine, but probably takes 15 minutes of labor per part. And I always manage to slip or lose focus and ruin one now and then :-)

200 of these per year would be about what we'd need. And there are about six other similar parts on the flume unit, so something like 1200 pieces per year; and this is the most difficult one; most of the others are simple 2D that could be cut from sheet and they're done.

[gravelbar]

Here's a drawing; sorry about the half-baked question, ya'll. I can see cutting the part out with the 1/4" slot and then doing the larger one after turning it.

The drilling is easy to do manually (we have to ream anyway). But current operation has at least seven steps from rough material to final product.

I am looking at the ShopBot Desktop for this; we have plenty of CAD and tech expertise in the shop, just no CNC yet.

[Simops]

Steve very doable in a Shopbot....I would consider something a bit bigger then a desktop to give you the Z height and to batch out a good quantity in one hit.

Place the 1.25" HDPE on the spoilboard and cut a nested batch of the piece profile with small groove and long hole. Then as said a couple of simple wooden jigs to hold a batch of pieces together in the other direction to do the larger groove and then another jig to turn part for small hole. The jigs are a one off make that will last. It's about batching out quantity.

You will find use for the bot in other areas of your manufacture. Example I use my bot to cut aluminium, thin sheet is a problem as I really need vacuum hold down but one day, one day. But I still use it a lot for batching out extruded aluminium angle that I need to cut a whole bunch of elongated holes precisely in line down the angle....a simple jig makes this easy, fast and precise ......

Good luck with what you come up with......

Cheers

[scottp55]

Steve, What is the width and depth of the dado that holds it on the rails? 2.75" is cutting Desktop pretty close on Z.

[gravelbar]

Micheal, thanks for your input, that's kind've what I had in mind, but I'm very new to CNC. I see you have a Buddy -- that one kind've scares me because it appears the tables is wood supported by rollers; i.e. you have a plywood on metal system, is that true? Do you have Z accuracy issues?

Scott, the "Dado" is 1" wide. And yes, the 4" Z on the SB Desktop is a problem for me, we have parts for our other machines that are 2" thick HDPE. I am kind've leaning towards CAMaster because of that (better Z and larger work surface for the money).

I'm all ears. Many thanks for the help, this is a big decision for me.

Steve

[scottp55]

Steve, 1" depth as well? Yeah we looked at Stinger as well, but once we added everything up The Desktop won out, and we really needed the accuracy. We found workarounds for almost everything we needed with the help of this forum. Saved enough to buy a second Desktop 6 months ahead of schedule.:)

[Rob Gunn]

Steve, The parts that you are showing that you need to machine are doable on the ShopBot. BUT If I were in your shoes, I would look at a small used CNC Mill. I have 25+ years as a toolmaker and the parts that you need would best be done on a more accurate and heavy duty machine. Don't get me wrong, I love my ShopBot and I do a lot of sign work and woodworking project but the ShopBot is just not as rigid as what I would want when it comes to true part manufacturing. Just my 2 cents worth...

[bearcat]

Steve,

A design thought would be to split the block lengthwise - left side / right side - then each side could be completely machined in the same operation and then a use few Pastite screws for quick assembly.

The DeskTop is a very capable machine. I've setup and run the current generation of larger ShopBots in production and am also using a DeskTop in production for smaller HDPE and acrylic parts. The DT cut quality, accuracy, and repeatibity is the best.

Ed

[gus]

Steve, You could also make the rack and the gear.

Check out this, it will export several formats.

http://woodgears.ca/gear_cutting/template.html

Gus

[gundog]

Steve,

A design thought would be to split the block lengthwise - left side / right side - then each side could be completely machined in the same operation and then a use few Pastite screws for quick assembly.

The DeskTop is a very capable machine. I've setup and run the current generation of larger ShopBots in production and am also using a DeskTop in production for smaller HDPE and acrylic parts. The DT cut quality, accuracy, and repeatibity is the best.

Ed

This is how I would do it. I cut a lot of UHMW but if you need a smooth finish I don't believe the SB will get you a good finish in UHMW. My finish is usually pretty rough in UHMW.

Mike

[Dennis Rech]

Micheal, thanks for your input, that's kind've what I had in mind, but I'm very new to CNC. I see you have a Buddy -- that one kind've scares me because it appears the tables is wood supported by rollers; i.e. you have a plywood on metal system, is that true? Do you have Z accuracy issues?
Steve

I have an older Buddy and it came with a 1/2 inch thick aluminum table.
I always thought that ShopBot made an error when they ceased providing the aluminum table. Financial reasons likely. I also have a power stick so I know about wood tables.
There is no reason that an aluminum table cannot be fitted to the newer Buddies. The aluminum table even came provided with a grid pattern of threaded holes. This is handy when I am working small items in that I can screw down a machinist vise directly to the table and hold the parts like a machinist would.
At one of the ShopBot camps, it was mentioned that the table is still an option. If you do the sort of work that would benefit from a metal table, you might want to give them a call.
Never a warp, nor a sag or need for resurfacing.