Back lash Compensation?

All info relating to the Denford Router 2600 and Pro CNC routers

Moderators: Martin, Steve, Mr Magoo

Post Reply
richgirling
Posts: 17
Joined: Thu 17 Jun , 2010 11:03 am

Back lash Compensation?

Post by richgirling » Mon 01 Nov , 2010 13:19 pm

Hello.

I have noticed that our 2600 Pro has some back lash present on the X axis.
I have attached a DTI to the bed and taken some readings

X Error of 0.12mm
Y Error of 0.08mm
Z Error of 0.02mm

The X axis error is so bad that you can see it by eye when you jog the machine using the 0.1mm setting!
Is there any backlash compensation settings to adjust? I have given the machine a good clean and lubricate with Swanslip before taking these readings.

Cheers
Rich.

User avatar
Steve
CNC Guru
CNC Guru
Posts: 1430
Joined: Tue 21 Feb , 2006 16:15 pm
Location: Denford UK

Re: Back lash Compensation?

Post by Steve » Mon 01 Nov , 2010 14:18 pm

Hi,

You should be able to remove the amount of backlash mechanically. If you can see that much there must be a way to correct it.

I would power off the machine and then turn the X screw by hand, you should be able to feel as well as see the problem.

The motor is a direct drive to the rear screw (via a coupling which could be loose) there is then a tooth belt drive that connects the rear screw to the front one. I would check the timing pullies are both ont the leadscrew shaft.

At the LH end of the leadscrews there is a castle nut which prevents end float in the screw.

The only other thing it could be is the antibacklash nut that secures the leg to the screw. These may need removing and cleaning out. Note you need to locate the position of these prior to removal. Drive the axis to the far end of its travel before refitting as the nut will then find its own centre.

richgirling
Posts: 17
Joined: Thu 17 Jun , 2010 11:03 am

Re: Back lash Compensation?

Post by richgirling » Mon 15 Nov , 2010 14:42 pm

Hi Steve.

Thanks for your reply.
I have checked the toothed drive belt is located on the pulleys (can't see them under the cover but can feel them).
I have removed, cleaned and lubricated the anti backlash nuts which attach the leg to the lead screw.
I have not been able to locate the castle nut on the LH end of the lead screw. Could you please email me a photo of what component you mean?

As I have investigated further it actually looks like the RH bearing on the front lead screw (X axis) has gone. I can get a small amount of liner movement by hand and the bearing is making a bit of noise as it changes direction.
This looks difficult to replace, please advise.

Cheers
Rich.

User avatar
Denford Admin
Site Admin
Posts: 3632
Joined: Fri 10 Feb , 2006 12:40 pm
Hardware/Software: Go to User Control Panel > Profile
Enter as much information about your CNC hardware and software as you can - it makes it easier for everyone to know what you're talking about then.
Location: Sunny Brighouse
Contact:

Re: Back lash Compensation?

Post by Denford Admin » Tue 16 Nov , 2010 14:55 pm

Just to let you know we're not ignoring you, we're looking into it with the aim of posting up some instructions / photos
This week is the Design & Technology Show NEC so its a very busy time for us.

richgirling
Posts: 17
Joined: Thu 17 Jun , 2010 11:03 am

Re: Back lash Compensation?

Post by richgirling » Tue 30 Nov , 2010 11:37 am

Bump.

I'm still awaiting some direction as how to correct this fault.

User avatar
Denford Admin
Site Admin
Posts: 3632
Joined: Fri 10 Feb , 2006 12:40 pm
Hardware/Software: Go to User Control Panel > Profile
Enter as much information about your CNC hardware and software as you can - it makes it easier for everyone to know what you're talking about then.
Location: Sunny Brighouse
Contact:

Re: Back lash Compensation?

Post by Denford Admin » Tue 30 Nov , 2010 11:49 am

Sorry the last I heard we were going to recommend you have a service visit as getting to the necessary bits involves removing the cabinet top and the machine from the base...
Here is the info I got from one of our designers:
Attached .pdf files illustrate the X axis bearing housings on the Router 2600.

There is no nut on the left hand end of the screw: the leadscrew is constrained axially by the inboard bearing in each of the two right hand bearing housings.

The bearing is constrained within the housing by the end plate, and the screw is constrained within the bearing by a Nyloc nut.

The outboard bearing in the right hand housing, and the bearing at the left hand of the screw give only journal constraint, and are allowed to float axially.

The movement detected could be due to bearing failure, the nut coming loose, or the endplate not being fully tightened against the end face of the housing and/or the outer race of the bearing. Only the third possibility is relatively easy to check. It may be possible to insert a packer between the plate and the bearing outer race (the outer race of the bearing should be proud of the housing face by between 0.05 and 0.1mm) to ensure that the bearing is fully clamped. It would be advisable to try this and recheck the backlash before proceeding with any of the other options.

To gain access to the Nyloc nut and/or the bearing would almost certainly require the removal of the cabinet top guard, and the machine itself from the cabinet.
Hope this helps - if not contact service :bert: denford :ernie: co :ernie: uk
PS - We are moving to new premises in a couple of weeks, so please bear with us !
Attachments
Router-2600-X-Axis-Bearings-Driven-(Front)-Side.pdf
(513.75 KiB) Downloaded 1362 times
Router-2600-X-Axis-Bearings-Drive-(Rear)-Side.pdf
(802.23 KiB) Downloaded 800 times

Post Reply