Why I Won't Specify Interroll Components Without Checking the Interroll CAD First

Honestly, I think a lot of conveyor design mistakes start before any drawing is even opened. People—me included—download the product PDF, skim the dimensions table, and assume that's enough. It's not. If you're specifying Interroll components without pulling the actual Interroll CAD model, you're setting yourself up for a very expensive surprise.

I'm the guy who handles conveyor component orders for a small systems integration shop. Over the last seven years, I've personally made and documented eleven significant specification errors. Together, they cost us roughly $14,000 in wasted parts, expedited shipping, and rework. So I'm not saying this from a 'look how smart I am' position. I'm saying it because I've got the invoice history to prove the opposite.

The mistake that convinced me

Back in 2017, we had a project for a small sortation line. I needed motorized rollers, so I found an Interroll product page that looked right, checked the key dimensions in the PDF, and ordered 47 pieces. The rollers showed up and the frame builder looked at me like I was an idiot. The shafts were too short for the side rails we had already cut. Not by a little—by 14 mm. It doesn't sound like much until nothing fits.

That order cost us about $1,850 in rework and a week of delay while we machined adapters. What frustrates me is that the CAD model—which I didn't bother downloading—showed the shaft detail clearly. A five-minute check would have caught it. That was the moment I created our pre-order CAD check list.

Why the PDF is not enough

PDFs are a summary, not the whole story. Interroll's product line is huge and modular. The drum motors, 24V rollers, EC310 drive controls, and the various frame and support components are designed to work together, but the interface details live in the 3D CAD models. Bolt patterns, cable exit positions, clearance for the drive control—those are things you often can't infer from a dimension table.

And here's where I'll admit a data gap: I don't have hard data on how many of our past mistakes were caused by missing CAD info versus, say, just me reading the table wrong. But based on the last eighteen months, we've caught 47 potential mismatches using the CAD-first workflow. That number comes from our own order tracker, so it's not scientific. Still, it's enough for me.

What a CAD check actually catches

One example: for a 24V roller with an EC310 drive control, the 2D document can make it look like the control unit sits neatly within the frame envelope. The STEP model shows that a connector and cable sweep space that you might be planning to use for a return belt. We found that in CAD on a recent quote, before cutting anything. It changed the whole drive layout.

Another example is shaft flattening or groove positions on drum motors. The tolerances can vary depending on the drive option. Again, the CAD model is the authoritative source. Maybe not the only source, but the closest one I've found to what actually arrives at the dock.

Using Interroll CAD the right way

The Interroll CAD library actually works. I'll be specific: it gives you models in multiple formats, so our mechanical designer can drop a roller directly into SolidWorks or whatever your team uses. It's not a simplified envelope model; it includes real mounting details. For those of us who learned on PDFs in the 2000s, it's worth unlearning the habit.

We also worked with Interroll Asia Pte Ltd on a few projects when our local distributor couldn't answer a technical question. Their support engineers use the same CAD library. When there's a question about fit or interface, they send a step file back, not a vague explanation. That collaboration alone probably saved us twice—well, maybe three times, I'd have to check our email archive.

If there were a first congress of conveyor integrators, my one proposal would be: no PO without a CAD check. It sounds simple, but it changes the conversation from 'I think this fits' to 'I've seen how this fits.'

A near-miss example

Earlier this year, we were quoting a pallet moving system. The customer wanted a specific speed and load, and I had a cross-reference chart open. Based on the chart, a certain 24V roller with a certain control option looked fine. But the CAD model showed that the drive control housing would stick out past the frame profile on our chosen layout. Was that a deal-breaker? For the envelope they had, yes. Without the CAD check, we might have quoted an impossible design.

So glad I checked the model first. Almost approved it using a 2D drawing from memory. That would have been one click away from ordering thirty-two wrong rollers.

Counterargument: 'CAD models used to be useless'

I can hear someone saying: 'Yeah, but half the time the CAD online is a simplified shape that doesn't match production.' That was true maybe ten years ago, when some manufacturers posted decorative 3D models and told you to request the 'real' model by email. Today, the major manufacturers—and Interroll is one of the better ones—keep their CAD library in sync with production drawings. It's not flawless, but it's far more reliable than a PDF dimension table that might be a revision old.

The other pushback is that checking CAD for every component ruins your speed. Honestly, it takes less time than arguing with the workshop later. On a recent 12-piece order, the CAD review took our designer maybe ten minutes. It caught one interface problem that would have caused at least a $900 redo. That's a good trade by any measure.

You might also say that if you only use standard conveyor modules from a single platform, you don't need to check CAD at all. I thought that too. Then we mixed two frame heights because the PDFs showed center distances differently. The modules themselves are great—actually, the modularity is what saves us—but you still need to verify the actual interfaces. 'Modular like Lego' is a nice phrase, but nobody would start a Millennium Falcon Lego build without checking the parts list. A conveyor system deserves the same level of care.

The assumption is that opening the CAD model is one extra step. The reality is that skipping the step is what creates the expensive redo. I've learned that the hard way, more than once.

Bottom line

I'm not saying CAD files replace good engineering. They don't. I'm saying that for Interroll components, the CAD model is the most reliable reference we have for what will actually show up at the dock. PDFs are for quick browsing and maybe for a customer file. The CAD is for the real decisions.

My rule now is simple: before you finish any bill of materials for an Interroll product, open the CAD model and look at the interfaces. If something looks off, raise the red flag then, not after fabrication. It's the cheapest insurance I know—it costs nothing but a few minutes, and it's saved us thousands.

That's my opinion. I've been wrong plenty of times, but the CAD-first habit is the fix that worked. Interroll has made it easy to check; not using that tool is on us.