By continuing to use this site, you agree to our use of cookies. Find out more
Forum sponsored by:
Forum sponsored by Forum House Ad Zone

Bearings or bushed

All Topics | Latest Posts

Search for:  in Thread Title in  
colin hamilton31/05/2022 20:10:48
140 forum posts
61 photos

So I'm looking to make a rotisserie smoker. Not like a hog roast where the spit is passed through the animal but more like a carrousel where 4 trays rotate round. Basically a smaller version of the attached photo. It will be used at relatively low temp (max approx 180). As with all my builds its about recycling so I'm looking for 'good enough' engineering and the opportunity to make bits. So far it's a barrel for the cooking part and a cut down gas bottle for the fire box.

I'm considering the main bearing options. I've got some spare bearings so was thinking of making some housed bearings which I would bolt onto the outside of the barrel but I'm a bit worried about the temp. Would bushes fair better? If yes would aluminium do (I already have some).

The main shaft us going to be 19mm pipe and it will be rotating at about 3 rpm.

Thanks Colin ⁷screenshot_20220531-195506_chrome.jpg

HOWARDT31/05/2022 20:15:41
932 forum posts
39 photos

Ball bearings have a maximum operating temperature usually around 60deg C, and any grease content will run out. Plain bearings would do, even steel on steel with slow running, probably more than adequate for the purpose.

AdrianR31/05/2022 20:35:19
597 forum posts
36 photos

You could always use a dry lube like Graphite or Molybdenum Disulphide on plain bearings

SillyOldDuffer31/05/2022 20:36:25
Moderator
8895 forum posts
1998 photos
Posted by HOWARDT on 31/05/2022 20:15:41:

Ball bearings have a maximum operating temperature usually around 60deg C,...

I hope that's not universally true - my car engine block runs hotter than that!

But I agree about plain bearings. Apart from the temperature, the bearings in a garden rotisserie have a slow lazy life. Sounds ideal for a steel shaft running in self lubricating cast iron. However, I'd be tempted to try Aluminium for cheapness if the design allowed them to be easily replaced if they seized or wore badly. Smearing the journals with Graphite would provide enough lube.

Dave

old mart31/05/2022 20:36:43
3908 forum posts
268 photos

Plain bearings would be best, and if you are concerned with temperature, you can get a tube of ceramic bearing grease which will be more than adequate, and plenty left over for other jobs.

John P31/05/2022 20:41:02
415 forum posts
265 photos

Aliexpress sell full ceramic bearings for somewhere around £4 each depending on size some will work up to

800 C only at low rpm (200) there are hundreds of them , type in " ball bearings high temperature" to scan through,not able to put reference on here as it will be taken down.

John

Martin Kyte31/05/2022 21:25:31
avatar
2793 forum posts
53 photos

Whats wrong with a between centres arrangement. Easy to dismantle.

regards Martin

bernard towers31/05/2022 21:29:19
691 forum posts
141 photos

Lubricate with chicken fat!!

Nigel Graham 231/05/2022 22:14:43
2287 forum posts
33 photos

Oh, this doesn't need anything too fancy especially if the shaft's bearing surface is just the raw pipe surface, but remember to lubricate the bearings well with grease before storing the rotisserie, as well as prior to use. Especially with aluminium bushes.

mgnbuk31/05/2022 22:35:53
1207 forum posts
72 photos

Graphite bushes, run dry

Nigel B.

Hopper31/05/2022 23:15:59
avatar
6690 forum posts
347 photos

3 rpm? Steel on steel should be fine.

Paul Lousick01/06/2022 02:01:25
2078 forum posts
727 photos

A BBQ is always covered with fat/grease after cooking. So self lubricating. Steel on steel bearings will probably outlast other parts of the grill.

colin hamilton01/06/2022 06:18:25
140 forum posts
61 photos

Brilliant thanks for the responses. Looks like I have plenty of options.

not done it yet01/06/2022 09:43:49
6888 forum posts
20 photos

Do you have a suitable motor for this project? 10HP would easily cope. Possibly just a little smaller?

Motor speed might be important? 2 or 4 pole motor? Two pole at 2800rpm might be the best?

Three phase with VFD or a brushless DC might be best for wide speed variation choices?

Add to this lot the huge fan required, to supply the combustion air, and you are nearly home. Automatic. ash pan, grate clearing, etc might be a high priority?

Might also need a chain saw to cut down the oak trees for the smoking chips. Saw can be electric, of course - better for the environment than using fossil fuels.

I think bearings are likely fairly low on your list of priorities.🙂

colin hamilton05/06/2022 11:38:35
140 forum posts
61 photos
p1000172.jpgPosted by not done it yet on 01/06/2022 09:43:49:

Do you have a suitable motor for this project? 10HP would easily cope. Possibly just a little smaller?

Motor speed might be important? 2 or 4 pole motor? Two pole at 2800rpm might be the best?

Three phase with VFD or a brushless DC might be best for wide speed variation choices?

Add to this lot the huge fan required, to supply the combustion air, and you are nearly home. Automatic. ash pan, grate clearing, etc might be a high priority?

Might also need a chain saw to cut down the oak trees for the smoking chips. Saw can be electric, of course - better for the environment than using fossil fuels.

I think bearings are likely fairly low on your list of priorities.🙂

Yep the things you mention I already have got covered off from when I built my hog roast machine. I'm really interested in improving the bearing set up hence my question but thanks for your inputsmiley

p1000174.jpgp1000172.jpgp1000172.jpg

All Topics | Latest Posts

Please login to post a reply.

Magazine Locator

Want the latest issue of Model Engineer or Model Engineers' Workshop? Use our magazine locator links to find your nearest stockist!

Find Model Engineer & Model Engineers' Workshop

Sign up to our Newsletter

Sign up to our newsletter and get a free digital issue.

You can unsubscribe at anytime. View our privacy policy at www.mortons.co.uk/privacy

Latest Forum Posts
Support Our Partners
Dreweatts
Eccentric July 5 2018
Rapid RC
cowells
Eccentric Engineering
Subscription Offer

Latest "Wanted" Ads
Get In Touch!

Do you want to contact the Model Engineer and Model Engineers' Workshop team?

You can contact us by phone, mail or email about the magazines including becoming a contributor, submitting reader's letters or making queries about articles. You can also get in touch about this website, advertising or other general issues.

Click THIS LINK for full contact details.

For subscription issues please see THIS LINK.

Digital Back Issues

Social Media online

'Like' us on Facebook
Follow us on Facebook

Follow us on Twitter
 Twitter Logo

Pin us on Pinterest

 

Donate

donate