Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here





I have come into possession of a very old Ro-Tap, made under license by Eberbach & Sons, Ann Arbor, MI. S/N 8817.
For those who might be familiar with these old machines, it is the model with the oil-filled base.
Tyler says it is obsolete and they can supply no parts.,
The only thing I need is the top lid and the cork block. Is there a reason why those items from a newer machine would not work? It is set up for 8" round sieves.
Does anyone have one of these just sitting around and would sell the top cap?

I have lusted/ desired/ wanted a Ro-Tap for the entire time I have been in this industry. Now that I am this close, I need to make it work. We got it from another firm which was going out of business. The manager of this office didn't know what it was and was ready to send it to the trash. I intervened.
Please help me save this vintage Ro-Tap.....or educate me why I should let it go to the junkyard.


I inherited one of these and passed it on to a testing firm friend. My son works for him and I still give reasonably free consulting advice. I'll check, but guess he may still want to use it. Otherwise that cap is pretty simple and any machine shop should be able to make one.
OG back here:
Well that machine is in use. The cover is a cast thing, but my son has it and can make a sketch of the dimensions so any shop, even he (my son) could make it, but no nicely machined (flame cut circle, etc.)

OG back: Well son figures making q new cover would be too expensive.

go to this link and you may find what you need. The parts likely can be made to fit if not the exact model.


Thanks, OG.
Exactly what I thought...its only a cover for the sieves and a holder for the cork block.
I was thinking I could have a local machine shop cut it out using their plasma cutter. I could rivet a regular 8" round sieve cover to the plate and provide whatever mounting ears or such that were needed to hold it in place. Do you think 1/4" steel would be heavy enough, or would 3/8" be better?


I have not had this machine in many years, but the diagram in the link shows a holder ring, so I would think machining and welding would need to make sure it fits. As to thickness the original casting probably is at least 3/4" in places so I'd opt for 1/2" thickness. That cork is pretty large diameter as I recall at least 1-3/4". You might look at something else than cork, say a chunk of hard rubber from a LARGE tire. It would not have to be round, but has to fit inside a collar of some sort welded to the plate. As I recall the cork sits up at least 1-1/2". Run the machine to see where the hammer has to be at the end of the blow.


Mike...great find! I've done similar with old Rainhart equipment. Well worth restoring.....just watch that it still meets ASTM standards. You might want to split a few samples and run through two machines to check.


Good idea, thanks, Ron

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Research Report: State of IoT Adoption in Product Development 2019
This research report, based on a survey of 234 product development professionals, examines the current state of Internet of Things (IoT) adoption by product design teams, its perceived importance, and what features and capabilities teams consider important when making decision about adding IoT functionality to their products. Download Now
Research Report: Augmented Reality for Maintenance, Repair and Overhaul (MRO)
The term Industry 4.0 denotes a cluster of technologies that’s poised to fundamentally reshape manufacturing and bring about a new industrial revolution. These include 3D printing (AM), the Industrial Internet of Things (IIoT), artificial intelligence (AI) and mixed reality technologies, more commonly known as virtual reality (VR) and augmented reality (AR). Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close