Need Help!- Spindle Mount for RotoZip

[Joe Lavery]

Hi all,

I've just bought a Rotozip tool that I want to use with my Zenbot CNC. Does anyone have a drawing or plan for such a thing. or any advice on how to go about making one.
I'm using a Dremel at the moment but it's not up to the job I need to cut.

Thanks in advance,
Joe.

[rich909]

Hi Joe --

Originally Posted by Joe Lavery <snip> I've just bought a Rotozip tool that I want to use with my Zenbot CNC. Does anyone have a drawing or plan for such a thing. or any advice on how to go about making one. I'm using a Dremel at the moment but it's not up to the job I need to cut. <snip> Joe.

On the bigger machines, the Z-axis base plate is about 4-7/8" x 6-7/8" and the spindle is attached by a pair of 'hoops' made out of 3/4" chunks of HDPE measuring about 4-7/8" x 4-7/8" that attaches to the plate with 2 bolts in each plate. Clamping is achieved by a third bolt at the outer edge of the hoop that adjusts the circular size of the hoop. If your dremel spindle mount is similar, I'd copy the part of the hoop attachment at the plate and scale the size the hoops to match the measured diameter of the Rotozip. Does that make sense?

I've attached a couple of photos that show the mount for the Colt on my Zenbot 1216. The idea would be to do something similar but sized for the Rotozip.

You didn't say what model Rotozip you got, and I understand the new ones are now Bosch Rotozip, with specs very similar to the Colt. Does it have a 'handle' like the earlier ones? If so can it be removed? Otherwise cutting the hoops can't be a simple circle.

I've seen a variety of non-factory spindle mounts and there are other ways to do it. Hopefully, someone can respond to you who has already done this one specifically. If not I hope this is of some help.

Worst case, you should be able to order the mount for your machine from Zenbotcnc.com for about $30. If you cut it yourself you will probably need a long reach end mill to cut the 3/4" HDPE profiles, and if you don't have the plastic on hand you may have to buy a bigger chunk than you actually need. All said, it may be worth it to order if from Shaun/Zenbot.

--Rich

[Joe Lavery]

Thanks very much Rich for your speedy and useful reply.

The model of the Rotozip is the Rebel. I already have a fair sized chunk of HDPE that I could use but as you say the Dremel would struggle to cut it.

I did send an email to Shaun over a week ago but no reply as yet. I mentioned that I'd recently bought the 1624 second hand so that may have some bearing on the lack of an answer.

I'm in the UK so the wait for post would be another issue; but if this is going to be a complicated job I might wait anyway! Assuming of course that Shaun eventually replies.

Sadly the Colt is not availabe in the UK either, so that was not an option.. I would have prefered to go that route in fact but I already have the Rotozip so I though I might as well use it if I could.

Regards
Joe.

[Joe Lavery]

One more thing Rich, can you tell me the size of the threaded holes in the base of the Zenbot.

Regards
Joe.

[rich909]

Hi Joe --

Originally Posted by Joe Lavery <snip> The model of the Rotozip is the Rebel. I already have a fair sized chunk of HDPE that I could use but as you say the Dremel would struggle to cut it.

I looked up the Rebel and it appears to be the one with the hard plastic handle making a mount more complicated. BTW, You may want to take a look at this link, if you haven't already seen it:
FAQ

Originally Posted by Joe Lavery <snip> I did send an email to Shaun over a week ago but no reply as yet. I mentioned that I'd recently bought the 1624 second hand so that may have some bearing on the lack of an answer. I'm in the UK so the wait for post would be another issue; but if this is going to be a complicated job I might wait anyway! Assuming of course that Shaun eventually replies.

The SPAM fairy may have gotten your message to Shaun. It is unlike him not to reply quickly. I'd give him another try.

I don't think it matters that you bought your machine used. The Zenbotcnc site has recently been upgraded and now has a forum. There is a thread on spindles so you could post your question there. Unfortunately, with the Rebel and early Rotozip models being discontinued, you might be on a dead end.

Originally Posted by Joe Lavery <snip> Sadly the Colt is not availabe in the UK either, so that was not an option.. I would have prefered to go that route in fact but I already have the Rotozip so I though I might as well use it if I could.

I got my Colt as a referb. from CPO through Amazon within the past 6-months. Is that a possibility for you in the UK? If not you might be able to do something similar through ebay. It seems a shame to expend a bunch of time and resources on a mount with a limited useful life.

Regarding your follow-up, I measured the bolts used in the mounts at 5.84mm (0.240) roughly 1-1/4" long, and they appear to be the same size used throughout the machine. I *believe* they are 1/4-20, but I am going from memory on this. I had one that was bad when I got my machine and I re-taped it. Anyhow if you talk to Shaun you could ask him to be sure. I am certain he will try to help you.

--Rich

[Joe Lavery]

Thanks again Rich, I'll give Shaun another try and perhaps I'll wait and get a more substantial router.
I see on the forum that the outer casing for the Rotozip is not really designed for mounting on the CNC. It appears to be too flimsy around the lower bearing, so if you attach a traditional mount it sqeezes the bearing and can cause it to fail.
Incidentally the Rebel I have does have a removable handle, these's a grey lever at the top that holds it in place. Not that it makes much difference in the circumstances.....

On another topic, what feed rate/ speed would you use with a 2mm end mill cutter on a piece of extruded acrylic? I ask becasue I've been doing some sample cuts and the acrylic heals itself behind the cutter. In some cases to the point where it stopped the router. Obviously I switched it off imediately. I've since founf that slowing the feed rate down did help some but if I slowed the Dremel down it couldn't handle even the lightest cut (.50mm).

I do appreciate your help,
all the best,

Joe.

[rich909]

Hi Joe --

Originally Posted by Joe Lavery <snip> On another topic, what feed rate/ speed would you use with a 2mm end mill cutter on a piece of extruded acrylic? I ask becasue I've been doing some sample cuts and the acrylic heals itself behind the cutter. In some cases to the point where it stopped the router. Obviously I switched it off imediately. I've since founf that slowing the feed rate down did help some but if I slowed the Dremel down it couldn't handle even the lightest cut (.50mm). <snip>

Probably three factors are at play here: speed, feed & cutter design.

You didn't mention the speed and feed rates you have tried, but I would normally use 30 to 40ipm with the Colt ...and a very light cut like 0.0138" for example. The Dremel may need to be as slow as 10ipm or less.

I would think the spindle speed needs to be under 8k, and perhaps only 5 to 6k RPM. Lastly, if you are using these ranges and still have melting issues, it may be the cutter. Having a good sharp end mill designed for plastic materials will help keep heat down.

I've also heard that it may help to 'pause' the job and allow the work and bit to cool to minimize the melting. Depending on how long the job runs that may not be much fun.

Hope this helps.

--Rich