I let them grind knives

Whenever I have to run a new errand that requires me to speak to someone in German, I spend at least 30 minutes with Google Translate trying to figure out exactly how to phrase my request. Recently, I finally worked up the motivation to take our kitchen knives to be sharpened (motivation being frustration at the dullness of the knives). I knew all the words that needed to be in the sentence: Messern (knives), schleifen (sharpen), and lassen (in this case, to have something done for you). But I didn’t know the correct word order. Here are just a few of the results from my attempts with Google Translate.

Ich lasse diese Messern zu schleifen./I’ll grind these blades.

Ich hätte gern diese Messern schleifen werden./I would be happy to grind these blades.

Ich hätte gern diese Messern schleifen lassen./I would have liked them sharpened these knives.

Ich lasse diese Messern schleifen./I let them grind knives.

And by far the best:

Ich habe drei Messern zum lassen schleifen./I grind to get three knives.

In the end all my translation work was in vain, as my conversation with the woman at the knife shop quickly had to switch to English when she started explaining that my knives were made in China/made of very soft metal/probably unsharpenable…which I don’t even understand in English. We’ll find out today when I go to pick them up and get the manager’s opinion on the sharpenability of the knives. Which means another 30 minutes with Google Translate before I head to the knife store.

German speakers: What’s the right way to ask, “I’d like to have these knives sharpened”?